Unarchiving Mailbox Items

Posted on August 14, 2021 by Michel de Rooij

With the introduction of Exchange 2010 at the end of 2009, a native feature was added to Exchange Server for which organizations required 3rd party products before that. The feature which I am talking about is Exchange’s Personal Archives, Online Archives, or In-Place Archiving as it is called nowadays.

Background
Archives were introduced at a time when Office 365 was in its early days, many organizations were running Exchange on-premises with mailbox quotas as bandwidth and storage were limited or relatively expensive. It was up to end users to make sure their mailbox remained within its limits, either by removing either old items, large items or just move them out of their mailbox to those pesky .PST files.

Archives introduced benefits such as lowering disk footprint by taking infrequently used items out of the primary mailbox (which then could only synchronize in full) to the archive, which is basically an additional mailbox for long-term storage. Exchange’s built-in Messaging Records Management (MRM) through retention policies and tags can be used for automatic moving of older items to the archive.

Archives also come with few downsides, especially in the early days. Most notably are perhaps clients not supporting archives at all, or searches not spanning both mailbox and archive. Also, and this is not to be underestimated, end users do not always grasp the concept of archives and the impact on the tasks and tools they use. It’s not uncommon to see people panicking about “missing data” in service tickets, only to discover their “missing data” was moved to their archive by the company retention policy after some digging.

In recent years, I have seen archives becoming less relevant, and organizations adopting the large mailbox concept in favor of lean and mean mailboxes with archives. There are still exceptions of course, usually in the form of substantial – usually shared – mailboxes. For those, staying with Exchange Online archives – and when needed auto-expanding archives – is usually still an option due to the different type of mailbox interaction, or to circumvent Exchange’s storage limitations or Outlook for Desktop’s synchronizing of offline cache files before issues might be seen. The maximum number of items per folder is such a limit, however these have been raised or done away with in recent years. Non-stubbing 3rd party archive solutions taking data out of Exchange can also be a option.

The Problem
Switching to the large mailbox concept creates a problem for those organizations that have already enabled in-place archives for their end users: How to get that data back from those archives to the primary mailbox. While retention policies can move data in opposite direction, there is no such thing as a reverse-retention policy. Also, not every organization would like to instruct end users to unarchive this contents themselves, as it is prone to failure, blocks Outlook for Desktop from doing anything else and might result in abandoned operations which limits future actions as moves are still happening in the background.

When investigating a possible solution I found that there is no other way to accomplish this, than to programmatically move contents from the in-place archive to the primary mailbox. While there is a ‘archive’ operation for mailbox items (which moves it to the assigned Archive folder, not the in-place archive) there is no other single API call to perform this task. Also, the solution would have to use Exchange Web Services, as a limitation in Microsoft Graph makes it incapable of moving messages between multiple mailboxes.

Note: If I overlooked something in this area, please let me know.

Solution
To help organizations accomplish this task, I wrote a PowerShell script which requires the following:

Exchange Server 2013 SP1 or later, or Exchange Online.
Exchange Web Services (EWS) Managed API 2.21 or later (how to, NuGet package exchange.webservices.managed.api).
When using OAuth, the MSAL library is required (NuGet package Microsoft.Identity.Client). Also, you need to have registered an App in Azure Active Directory; the Tenant ID, Application ID and certificate or secret is what you need to provide the script with to operate successfully.
In addition to installing the NuGet packages, you can also store the DLLs in the same folder as the script.

Note: Untested with Primary mailboxes on-premises and Exchange Online Archives.

The script Invoke-Unarchive will perform the following tasks:

Invoke-Unarchive will move contents from the in-place archive back to the primary mailbox.
The most optimal operation will be chosen:
- Folders present in archive but not in primary mailbox will be moved in one operation.
- Folders present in archive and primary mailbox are merged. Items in those folders are moved in batches.
- The same steps are repeated recursively per folder for the whole archive.
If, after moving, a folder in the archive is empty, and it is not a non-removable well-known folder, it will be removed.
Optionally, Invoke-Unarchive can also move contents stored in the Recoverable Items from the archive to the primary mailbox.
Invoke-Unarchive will handle throttling, either by honoring the returned back-off period or by adding delays between operations.
Moving items is asynchronous, and Invoke-Unarchive needs to wait for Exchange to complete the previous move to folder X before it can move the next set of items to folder X.

Do not forget to reassign retention policies causing archival, or you might have the run the script again at later moment.

Syntax
The parameters to call Invoke-Unarchive.ps1 are:

Identity to specify one or more mailboxes to unarchive items for.
Server to specify the FQDN of the Client Access Server to use. When omitted, Autodiscover will be used.
IncludeRecoverableItems to instruct the script to process deletions stored in the Recoverable Items as well.
Impersonation to use impersonation when accessing the mailbox. When using modern authentication (OAuth), impersonation is mandatory.
Force to force moving of items without prompting.
NoProgressBar to prevent progress status.
TrustAll to accept all certificates including self-signed certificates.
TenantId specifies the ID of the Tenant when using a mailbox hosted in Exchange Online.
ClientId to specify the Application ID of the registered application in Azure Active Directory.
Credentials to specify the Basic Authentication credentials for on-premises usage or against Exchange Online when OAuth is not an option.
CertificateThumbprint is the thumbprint of the certificate to use for OAuth. The certificate with the public key needs to stored with the registered application for authentication. The certificate with the private key should be present in the local certificate store.
CertificateFile and CertificatePassword to specify the file of the certificate to use. The file shoud contain the private key, and the password to unlock the file can be specified using CertificatePassword.
Secret can be used to specify the secret to authenticate using the registered application.

Note that Credentials, CertificateThumbprint, CertificateFile + CertificatePassword and Secret are mutually exclusive.

Example
Below shows an example run against a test-mailbox using modern authentication (OAuth). The common parameter Verbose is used to display additional output.

.\Invoke-Unarchive.ps1 -Identity michel@myexchangelabs.com -Server outlook.office365.com -Impersonation -Secret <Secret> -TenantId <Tenant> -ClientId <AppId> -Verbose

You can find the script on GitHub here.

Final Notes
The EWS operation – especially moving items – is not necessarily slow, but against Exchange Online processing large archives can take considerable amount of time due to throttling. When moving a significant number of items using Outlook for Desktop, you will likely run into Outlook abandoning the operation after which you need to wait for Exchange to finish pending moves before you can continue with this task. Using the script, you can take away this unarchiving task from end users by running the operation in the background in one or multiple runs.

MVPs around the World (2021)

Posted on July 29, 2021 by Michel de Rooij

A new Microsoft MVP award cycle, a new moment to have a look at the MVP statistics. Below numbers are taken from the public MVP site. While July 1st is the first day of the new award cycle, it usually is recommended to wait few days for the site and data behind it to get updated. and new and renewed awardees turning in their Non-Disclosure Agreement before showing up on the site. Because people get awarded every month, the comparison to July of every year should give an idea of the yearly trend.

Disclaimer: A percentage of MVP awardees are anonymous, and do not disclose information regarding expertise or location. There are currently 133 anonymous MVPs, and they are not taken into account in below statistics.

The following table contains the awardees per award category from July of 2019, 2020 and 2021, and change percentage compared to the year before. I will leave the interpretation up to you.

Expertise	Jul2019	Jul2020	%	Jul2021	%
Cloud and Datacenter Management	232	209	-10%	219	5%
Microsoft Azure	409	463	13%	534	15%
Office Apps & Services	491	512	4%	556	9%
Business Applications	166	240	45%	323	35%
Data Platform	332	358	8%	392	9%
Developer Technologies	644	697	8%	770	10%
Enterprise Mobility	106	113	7%	133	18%
AI	84	122	45%	138	13%
Office Development	47	64	36%	69	8%
Windows Development	119	110	-8%	120	9%
Windows and Devices for IT	57	43	-25%	42	-2%
Total	2687	2931	9%	3296	12%
Count	2634	2849	8%	3223	13%

Note: The total number of MVPs doesn’t equal the total number of awardees, as MVPs can be awarded in more than one category. A total of 77 MVPs are awarded in two or more categories.

When zooming in on the Office Apps & Services category, the awards per country are shown below, including the % change compared to last year. As you might notice, there are quiet a number of new countries being represented: Ghana, Greece, Peru, Senegal and Vietnam. This supports the current Diversity & Inclusion mindset, and in my opinion is a good thing.

Country	Number	Country	Number	Country	Number	Country	Number
AUS	26 (8%)	FRA	22 (22%)	NZL	6 (0%)	LKA	1 (0%)
AUT	3 (0%)	DEU	30 (25%)	NGA	3 (50%)	SWE	10 (11%)
BEL	5 (0%)	GHA	1 (100%)	NOR	6 (0%)	CHE	3 (0%)
BIH	1 (0%)	GRC	1 (100%)	PAK	1 (0%)	TWN	4 (0%)
BRA	10 (25%)	HUN	2 (0%)	PER	1 (100%)	THA	2 (0%)
BGR	3 (50%)	IND	12 (-8%)	POL	6 (0%)	NLD	22 (0%)
KHM	1 (0%)	IRL	2 (100%)	PRT	3 (0%)	TUR	2 (0%)
CAN	34 (3%)	ISR	3 (200%)	RUS	9 (0%)	UKR	2 (0%)
CHN	17 (0%)	ITA	5 (0%)	SAU	1 (0%)	ARE	2 (100%)
COL	6 (20%)	JPN	20 (0%)	SEN	1 (100%)	GBR	38 (15%)
HRV	5 (0%)	KOR	14 (16%)	SRB	1 (0%)	USA	131 (6%)
CZE	2 (0%)	MKD	2 (0%)	SGP	4 (33%)	URY	1 (0%)
DNK	6 (0%)	MYS	1 (0%)	SVK	1 (0%)	VNM	1 (100%)
EGY	1 (0%)	MEX	7 (40%)	SVN	2 (0%)
SLV	1 (0%)	MMR	1 (0%)	ZAF	4 (0%)
FIN	6 (50%)	NPL	1 (0%)	ESP	14 (16%)

And finally, the number of Office Apps & Services and total number of MVP’s over the last years.

OAS & Total PER CYCLE	Jul2017	Jul2018	Jul2019	Jul2020	Jul2021
Office Apps & Services MVPs	449	383	491	512	535
% Change		-15%	28%	4%	4%
Total MVPs	3490	3030	2634	2849	3223
% Change		-13%	-13%	8%	13%

If you have questions or comments, please leave them in the comments below.

Security Updates Exchange 2013-2019 (Jul2021)

Posted on July 13, 2021 by Michel de Rooij

Update July 20th: Added VC++2012 requirement to tip on running MT to prepare Exchange 2013 schema separately.

Another month, another Patch Tuesday! A quick blog on the July’s security updates for Exchange Server 2013 up to 2019.

The vulnerabilities addressed in these security updates are:

Vulnerability	Category	Severity	Rating
CVE-2021-31196	Remote Code Execution	Important	CVSS:3.0 7.2 / 6.3
CVE-2021-34470	Elevation of Privilege	Important	CVSS:3.0 8.0 / 7.0
CVE-2021-33768	Elevation of Privilege	Important	CVSS:3.0 8.0 / 7.0
CVE-2021-31206	Remote Code Execution	Important	CVSS:3.0 7.6 / 7.1

Note:

When looking at the MSRC information, you will notice 3 additional CVE issues addressed for July 13th. However, as far as I can see CVE-2021-34473, CVE-2021-34523 and CVE-2021-33766 were addressed in the April 2021 and eventually the May 2021 Security Updates, which also would explain MSRC’s mention of earlier CUs, such as Exchange 2019 CU8.
CVE-2021-31206 was the vulnerability discovered at the Pwn2Own 2021 contest.

Vulnerabilities mentioned in the table above are addressed in the following security updates:

Exchange	Download	Build	KB
Exchange 2019 CU10	Download	15.2.922.13	KB5004780
Exchange 2019 CU9	Download	15.2.858.15	KB5004780
Exchange 2016 CU21	Download	15.1.2308.14	KB5004779
Exchange 2016 CU20	Download	15.1.2242.12	KB5004779
Exchange 2013 CU23	Download	15.0.1497.23	KB5004778

Notes:

CVE-2021-33768 does not seem applicable to Exchange 2019 CU9 or Exchange 2016 CU20.
CVE-2021-34470 is only addressed in the security update for Exchange 2013 CU23.

More detailed information can be found at the original blog post here, which mentions some specific post-deployment instructions:

When running n-1 CU of Exchange 2019 (CU9) or Exchange 2016 (CU20), and you do not plan to upgrade to the latest CU yet but do wish to install this Security Update, you must also update the AD Schema using the CU10 or CU21 installation files.
When you are running Exchange 2013 CU23 in your organization, and no later Exchange builds are present, you need to deploy a schema update immediately after deploying the Security Update. After deploying the SU, from an elevated CMD prompt, run Setup.exe /PrepareSchema /IAcceptExchangeServerLicenseTerms from Exchange’s bin folder. You you need to separate the update from deploying the update, see end of article for a tip.

The blog also mentions some issues, which are identical to the ones mentioned with the May 2021 Security Updates:

Accounts ending in ‘$’ cannot use EMS or access the ECP.
Cross-forest Free/Busy might stop working resulting in 400 Bad Request (solution).
Running cmdlets against EMC using invoked runspace might result in no-language mode error (info).

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU9 to Exchange 2019 CU8. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU9-KBXXXXXX-x64-en.msp.

On another note, after deploying the security updates Exchange will start reporting its version number in the HTTP response header.

As a reminder, run the Security Update from an elevated command prompt to prevent issues during installation. In other words: Do not just double-click on the .MSP file. And on a final note, as with any patch or update, I’d recommend to apply this in a acceptance environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach. The rating implies a form of urgency.

OWA/ECP and HMAC errors
There are reports of the Security Update breaking OWA/ECP. Symptoms are browsers displaying an HMAC error:

Server Error in '/owa' Application.

ASSERT: HMACProvider.GetCertificates:protectionCertificates.Length<1
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
    
Exception Details: Microsoft.Exchange.Diagnostics.ExAssertException: ASSERT: HMACProvider.GetCertificates:protectionCertificates.Length<1

It is likely related to “Microsoft Exchange Server Auth Certificate”, which can be expired, invalid or for other reasons not being picked up. The reported solution is renewing the “Microsoft Exchange Server Auth Certificate”. This procedure can be found here. Do note that it may take an hour for the certificate to become effective. Meanwhile, you can check the comments in the original Exchange Team post, which is lively with feedback and responses.

Exchange 2013 CU23 SU & Schema Updating
Because with Exchange 2013 CU23 schema preparation needs to occur immediately after deploying the SU on (the first) Exchange 2013 CU23 server, a tip might be that you could deploy Exchange 2013 CU23 Management Tools on a workstation, install the SU on that workstation, then run the PrepareSchema from there before deploying the SU on any Exchange 2013 CU23 server.

This might also be helpful in multi-domain organizations, or organizations where AD and Exchange are managed by different teams or require separate changes. Note that performing the schema update this way requires Visual C++ 2012 Runtime, otherwise you will run into a “Exchange Server setup didn’t complete the operation” and the ExchangeSetup.log will contain “Could not load file or assembly ‘Microsoft.Exchange.CabUtility.dll”.

Exchange Updates – June 2021

Posted on June 29, 2021 by Michel de Rooij

The Exchange Team released the quarterly Cumulative Updates for Exchange Server 2019 and Exchange 2016. Biggest change for both editions is support for Anti-Malware Scan Interface (AMSI) integration, available on Windows Server 2016 and Windows Server 2019. It allows real-time scanning of HTTP payloads, blocking known malicious content before it reaches Exchange.

Links to the updates as well as a description of changes and fixes are described below. The column Schema and AD indicate if the CU contains Schema (/PrepareSchema) and Active Directory (PrepareAD) changes compared to the previous CU.

Version	Build	KB	Download	UMLP	Schema	AD
Exchange 2019 CU10	15.2.922.7	KB5003612	Download		Y	Y
Exchange 2016 CU21	15.1.2308.8	KB5003611	Download	UMLP	Y	Y

Exchange 2019 CU10 fixes:

5004612 Message body not displayed in OWA if the message was added in Outlook to a new mailbox
5004613 OutOfMemory exception when moving a public folder that has a large ICS sync state
5004614 Korean text is garbled in calendar invitation to a user with a Chinese display name
5004615 “InvalidOperationException” and Store Worker process crashes during mailbox move
5004616 Changing the email address in EAC doesn’t work in modern browsers
5004617 TLS 1.2 is not set as default after you install Exchange 2019 with Edge Transport role
5004618 MSExchangeMailboxAssistants 4999 Crash in ELCAssistant.InvokeInternalAssistant with System.NullReferenceException
5004619 Mailbox creation through ECP fails after installing Exchange Server 2019 or 2016 April update
5004622 “Cannot Send Mail – Your mailbox is full” error when you use iPhone mail to send very large attachments
5004623 PrepareADSchema required because of Active Directory schema change

Exchange 2016 CU21 fixes:

5004612 Message body not displayed in OWA if the message was added in Outlook to a new mailbox
5004613 OutOfMemory exception when moving a public folder that has a large ICS sync state
5004614 Korean text is garbled in calendar invitation to a user with a Chinese display name
5004615 “InvalidOperationException” and Store Worker process crashes during mailbox move
5004616 Changing the email address in EAC doesn’t work in modern browsers
5004618 MSExchangeMailboxAssistants 4999 Crash in ELCAssistant.InvokeInternalAssistant with System.NullReferenceException
5004619 Mailbox creation through ECP fails after installing Exchange Server 2019 or 2016 April update
5004622 “Cannot Send Mail – Your mailbox is full” error when you use iPhone mail to send very large attachments
5004623 PrepareADSchema required because of Active Directory schema change
5004629 No version updating after you install Exchange Server 2016

Notes:

If these Cumulative Updates contain schema changes compared to the Cumulative Update you have deployed, you need to run Setup with /PrepareSchema. If they contain Active Directory changes, you need to run /PrepareAD. Alternatively, permissions permitting, you can let Setup perform this step. Consult the Exchange schema versions page for version number comparison.
When upgrading from an n-2 or earlier version of Exchange, or an early version of the .NET Framework, consult Upgrade Paths for CU’s & .NET.
Don’t forget to put the Exchange server in maintenance mode prior to updating. Regardless, setup will put the server in server-wide offline mode post-analysis, before making actual changes.
When using Exchange hybrid deployments or Exchange Online Archiving (EOA), support requires you to trail at most one version (n-1).
If you want to speed up the update process for systems without internet access, you can follow the procedure described here to disable publisher’s certificate revocation checking.
Cumulative Updates can be installed directly; no need to install RTM prior to installing Cumulative Updates.
Once upgraded, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles.
The recommended upgrade order is internet-facing, non-internet-facing servers first, followed by Edge Transports.

Caution:

As for any update, I recommend to thoroughly test updates in a test environment prior to implementing them in production. When you lack such facilities, hold out a few days and monitor the comments on the original publication or forums for any issues.

Security Updates Exchange 2013-2019 (May2021)

Posted on May 11, 2021 by Michel de Rooij

Another month, another Patch Tuesday! A quick blog on May’s security updates for Exchange Server 2013 up to 2019.

These fixes address the following vulnerabilities:

Vulnerability	Category	Severity	Rating
CVE-2021-31209	Spoofing	Important	CVSS:3.0 6.5 / 5.7
CVE-2021-31207	Security Feature Bypass	Moderate	CVSS:3.0 6.6 / 5.8
CVE-2021-31198	Remote Code Execution	Important	CVSS:3.0 7.8 / 6.8
CVE-2021-31195	Remote Code Execution	Important	CVSS:3.0 6.5 / 5.7

These vulnerabilities can be fixed by single security update for Exchange, which you can find below:

Exchange	Download	Build	KB	Supersedes
Exchange 2019 CU9	Download	15.2.858.12	KB5 003435	KB5001779
Exchange 2019 CU8	Download	15.2.792.15	KB5 003435	KB5001779
Exchange 2016 CU20	Download	15.1.2242.10	KB5 003435	KB5001779
Exchange 2016 CU19	Download	15.1.2176.14	KB5 003435	KB5001779
Exchange 2013 CU23	Download	15.0.1497.18	KB5 003435	KB5001779

More detailed information can be found at the original blog post here, which also mentions some known issues and workarounds which you might encounter after deploying these updates.

Also, run the Security Update from an elevated command prompt, to prevent issues during installation (other words: Do not just double-click on the .MSP file). And on a final note, as with any patch or update, I’d recommend to apply this in a acceptance environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach. The rating implies a form of urgency.

Tagging External Messages

Posted on May 5, 2021 by Michel de Rooij

Two years ago, I posted a blog on how to implement Transport Rules in Microsoft Exchange to flag messages originating from outside the organization. Goal is to aid end users in identifying messages originating from outside of the organization, by displaying tags in the subject or body part of received messages. This to make them aware – and hopefully more cautious – when it comes to clicking links or opening attachments. Downside of this method is that every inbound message gets a bit cluttered in their subject or body with tags and notifications, which becomes more evident when replying back and forth to external messages. Back then, I already stated a sort of MailTip would be a more preferable and elegant solution.

Onward to 2021, where tagging of external messages became a generally available feature in March for Exchange Online (MC243047, announcement), when used together with Outlook for Web Access (OWA), Outlook for Mac, Outlook Mobile. Outlook for Desktop will also receive support for the feature (supported per version 2105 build 14026.20000, InsiderFast currently). To start adopting this tagging mechanism for new messages, organizations need to deploy an organization level setting using Set-ExternalInOutlook, e.g.

Set-ExternalInOutlook -Enabled $True -AllowList 'contoso.com'

This will enable the tagging of external messages in your tenant, except for domains or e-mail addresses which have been specified through the AllowList. In the example above, messages from contoso.com senders will bypass tagging. The AllowList is limited to 30 entries or 1 kB, whichever comes first. You can reconfigure the AllowList through the hashtable method, e.g.

Set-ExternalInOutlook –AllowList @{Add='fabrikam.com','john@wingtiptoys.com'; Remove='contoso.com'}

After configuring Set-ExternalInOutlook, tagging is not immediate and can take a short while to become active. To inspect current settings, run Get-ExternalInOutlook.

How tagged mail is presented depends on the client. For example, Outlook for Web Access displays an ‘External’ label in the message list, as well as a MailTip at the top of the e-mail contents:

Same goes for Outlook Mobile, where the message list as well as the message view will show an indicator:

Outlook for Desktop
However, Outlook for Desktop does not present a label in the message list, nor exposes a field to filter those external messages, only displaying a MailTip after opening the message:

So, people almost started asking right away if it was not possible to expose External information in the message list. Well, with a little help of “Oldskool” Outlook and forms customization, this is possible, and here is how:

First, we need information related to the MAPI attribute. As the field is not by default available in Outlook, we need to know some of its properties to define it later on. As mention in some of the documents, or Glen Scales’ article on how to identify messages using Graph or Exchange Web Services, the MAPI property tag is 41F28F13-83F4-4114-A584-EEDB5A6B0BFF and its name is IsExternalSender.

Next, we need to construct a .CFG file where we will define the property we want to expose. I’ve already done this part for you, and you can download IsExternalSender.cfg from GitHub. Also download the two .ico files and put them in the same folder as the .cfg file. Note that those .ico files only represent the form. Alternatively, you can copy the .cfg file to your Personal Forms Library folder and skip installing, but this way the instruction is a bit simpler, allows you to pick the Folder Forms Library and will skip the elevated access dialog as the Personal Forms Library is a protected folder.

Open Outlook, go to File > Options > Advanced and click the Custom Forms button. There, click Manage Forms. By default, the form is installed in your Personal Folder Library. You can also pick a mailbox to store the form, allowing it to roam together with the view changes we will perform later. Click Install and pick the prepared .cfg file you downloaded from GitHub, and the following dialog should be shown:

Click OK to confirm you want to load the information in the form file in your personal forms library and close the Forms Manager. Going back to the Outlook navigation view, you can now add an IsExternalSender field to the message list. Right-click the field header and select Field Chooser. In the drop-down list, select Forms.., and add External Tagging Form to the Selected Forms. Field Chooser should now display an available field named IsExternalSender, which you can add to your current view using drag & drop.

Note that the .cfg defines the IsExternalSender as Boolean and showing it as an Icon. This means that for External messages, the column IsExternalSender will contain a checkbox:

When you want, you can create custom fields to adjust how the information is presented. For example, you can create a custom field using a formula to display [EXTERNAL] for IsExternalSender messages, which might be more usable in certain views instead of the checkbox. To accomplish this, select New in Field Chooser,and create a field named ExternalTag, type Formula and enter the following formula:

iif([IsExternalSender]=-1,"[EXTERNAL]","")

You can then add the ExternalTag field to Compact View. Do note the text takes up a row in Compact view, thus might replace sender or the subject depending on layout and field order.

On a final note, when wanted you can filter, sort or create Search Folders using the new IsExternalSender field.

Exchange On-Premises
Organizations running Exchange Hybrid, routing inbound messages through Exchange Online, are not able to benefit from external e-mail tagging. IsSenderExternal is only stamped on messages destined for mailboxes in Exchange Online. These organizations have therefor no way to identify these messages landing in their Exchange on-premises environment, and may require them to deploy the less elegant Transport Rules solution regardless.

Security Update Exchange 2013-2019 (Apr2021)

Posted on April 13, 2021 by Michel de Rooij

15Apr2021: Added note about Pwn2Own vulnerabilities not being addressed by these updates.

A quick blog on April’s security updates for Exchange Server 2013 up to 2019. Details regarding these vulnerabilities are confidential, but organizations are recommended to install these updates based on their rating. With patching procedures still fresh in everyone’s memory, and every Exchange on-premises server being current after the Hafnium issues, that should not be a problem, right?

The fixes address the following Remote Code Execution vulnerabilities:

Vulnerability	Severity	Rating
CVE-2021-28483	Critical	CVSS:3.0 9.0 / 7.8
CVE-2021-28482	High	CVSS:3.0 8.8 / 7.7
CVE-2021-28481	Critical	CVSS:3.0 9.8 / 8.5
CVE-2021-28480	Critical	CVSS:3.0 9.8 / 8.5

More detailed information can be found at the original blog post here. Note that the recently discovered at the Pwn2Own 2021 contest are not (yet) addressed by these updates, according to this blog by the contest organizers.

The exploit can be fixed by single security update, which you can find below.

Exchange	Download	Build	KB	Supersedes
Exchange 2019 CU9	Download	15.2.858.10	KB5001779
Exchange 2019 CU8	Download	15.2.792.13	KB5001779
Exchange 2016 CU20	Download	15.1.2242.8	KB5001779
Exchange 2016 CU19	Download	15.1.2176.12	KB5001779
Exchange 2013 CU23	Download	15.0.1497.15	KB5001779

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2016 CU20 to Exchange 2016 CU19. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU9-KB5001779-x64-en.msp.

Change Teams Guest Profile Picture

Posted on April 11, 2021 by Michel de Rooij

In tenants with lots of Guests, the massive display of user initials – the default profile picture – isn’t very pleasing to the eye. Now while regular user can change their profile picture, Guest users cannot. Therefor, a long standing and popular request on UserVoice has been the ability to change profile pictures for Guest users. End of 2020, this request was updated, indicating a change was planned to incorporate the ability to change this profile picture. No signs on the roadmap yet, so what options – if any – does one currently have?

Last week, Teams MVP Yannick Reekmans posted a blog containing instructions on how to change your profile picture for tenants in which you are a Guest. It requires quite some steps and fiddling to accomplish this. One might also wonder, isn’t this possible “the programmatic way”? Well, yes, and here are the steps:

First, open up PowerShell, install the AzureAD PowerShell module it is not yet installed using Install-Module AzureAD, and connect to Azure Active Directory, specifying the tenant where you are a guest:

Connect-AzureAD -TenantDomain contoso.onmicrosoft.com

When the authentication challenge pops up, specify the credentials of the Guest account and approve the Multi-Factor Authentication challenge when required.

Next, use Set-AzureADUserThumbnailPhoto to set the profile picture for your Guest account, specifying your User Principal Name as ObjectId, as well as the picture you want to use, e.g.

Set-AzureADUserThumbnailPhoto -ObjectId 'michel_fabrikam.com#EXT#contoso.onmicrosoft.com' -FilePath 'c:\pic.jpg'

Regarding the User Principal Name, you can use Yannick’s method of determining your Guest’s ID. You can also try to guesstimate it by taking the e-mail address of your original account, replacing ‘@’ with ‘_’, adding a trailing #EXT# followed by ‘@’ and the default domain of the hosting tenant. The picture can be JPEG or PNG format, size 100kb at most, and square dimensions work best.

To verify the image has been set successfully, use Get-AzureADUserThumbnailPhoto -ObjectId <ID>. Then, have some patience for the change to propagate throughout the directories and caching mechanisms. To verify your update was successful and your picture looks properly, you can close the Teams client, clear the locally cached Teams data by removing everything under %AppData%\Microsoft\Teams (Windows), and start Teams again.

To easily spot tenants where you are a guest user and not a regular user, you might want to alter your standard issue profile picture a bit. For example, I have added a text label ‘Guest’ to mine. It doesn’t look as good as the high resolution photos that you can store in Exchange Online, but it certainly looks less boring than a set of intilials.

Note that all of the above is not an officially supported way to manage this picture. So, until there is one, these steps might help you out.

Exchange Updates – March 2021

Posted on March 16, 2021 by Michel de Rooij

The Exchange Team released the quarterly Cumulative Updates for Exchange Server 2019 as well as Exchange 2016. Be advised that both of these CUs include the March security update KB5000871. AExchange 2016 will receive its final CU in March, 2021.

Version	Build	KB	Download	UMLP	Schema	AD
Exchange 2019 CU9	15.2.858.2	KB4602570	Download		N	Y
Exchange 2016 CU20	15.1.2242.4	KB4602569	Download	UMLP	N	Y

Exchange 2019 CU9 fixes:

5001181 Certain search scenario can’t return expected result in Outlook online mode in Exchange Server 2019
5001182 Can’t use keyword “TMM” in a special pattern to search email in Exchange Server 2019
5001183 Attachment is treated as bad zip file on Edge Transport server in Exchange Server 2019 and 2016
5001184 EAC has no option to select the correct tenant for an Office 365 mailbox in Exchange Server 2019 and 2016
5001185 EAC has no option to select an archive domain for cloud-based archive in Exchange Server 2019 and 2016
5001186 Encoding of special characters isn’t preserved which causes missing text in Outlook in Exchange Server 2019 and 2016
5001188 Incorrect MRM properties stamped on mail item delivery when sending to multiple mailboxes on the same database in Exchange Server 2019 and 2016
5001189 Mailbox Audit log searches and Outlook both tied to MaxHitsForFullTextIndexSearches in Exchange Server 2019 and 2016
5001190 MonitoringGroup can’t control the placement of CAS monitoring mailboxes in Exchange Server 2019 and 2016
5001192 Microsoft Teams fails to show calendar because Autodiscover v2 isn’t site-aware in Exchange Server 2019 and 2016
5001193 New health mailboxes for databases are created every time Exchange Health Manager service is restarted
5001194 RFC certificate timestamp validation in Exchange Server 2019 and 2016
5001195 UPN specified when creating mailbox is overwritten automatically causing login failures in Exchange Server 2019 and 2016
5000631 Event IDs 1003, 1309 and 4999 are logged after installing Exchange Server 2019 CU8
4583558 PDF preview function in OWA leads to download action unexpectedly

Exchange 2016 CU20 fixes:

5001183 Attachment is treated as bad zip file on Edge Transport server in Exchange Server 2019 and 2016
5001184 EAC has no option to select the correct tenant for an Office 365 mailbox in Exchange Server 2019 and 2016
5001185 EAC has no option to select an archive domain for cloud-based archive in Exchange Server 2019 and 2016
5001186 Encoding of special characters isn’t preserved which causes missing text in Outlook in Exchange Server 2019 and 2016
5001188 Incorrect MRM properties stamped on mail item delivery when sending to multiple mailboxes on the same database in Exchange Server 2019 and 2016
5001189 Mailbox Audit log searches and Outlook both tied to MaxHitsForFullTextIndexSearches in Exchange Server 2019 and 2016
5001190 MonitoringGroup can’t control the placement of CAS monitoring mailboxes in Exchange Server 2019 and 2016
5001192 Microsoft Teams fails to show calendar due to Autodiscover v2 isn’t site aware in Exchange Server 2019 and 2016
5001193 New health mailboxes for databases are created every time Exchange Health Manager service is restarted
5001194 RFC certificate timestamp validation in Exchange Server 2019 and 2016
5001195 UPN specified when creating mailbox is overwritten automatically causing login failures in Exchange Server 2019 and 2016
4583558 PDF preview function in OWA leads to download action unexpectedly

Notes:

If these Cumulative Updates contain schema changes compared to the Cumulative Update you have deployed, you need to run Setup with /PrepareSchema. If they contain Active Directory changes, you need to run /PrepareAD. Alternatively, permissions permitting, you can let Setup perform this step. Consult the Exchange schema versions page for object version numbers.
When upgrading from an n-2 or earlier version of Exchange, or an early version of the .NET Framework, consult Upgrade Paths for CU’s & .NET.
Don’t forget to put the Exchange server in maintenance mode prior to updating. Regardless, setup will put the server in server-wide offline mode post-analysis, before making actual changes.
When using Exchange hybrid deployments or Exchange Online Archiving (EOA), support requires you to trail at most one version (n-1).
If you want to speed up the update process for systems without internet access, you can follow the procedure described here to disable publisher’s certificate revocation checking.
Cumulative Updates can be installed directly; no need to install RTM prior to installing Cumulative Updates.
Once upgraded, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles.
The recommended upgrade order is internet-facing, non-internet-facing servers first, followed by Edge Transports.

Caution:

Security Update Exchange 2010-2019 (Mar2021)

Posted on March 2, 2021 by Michel de Rooij

Update 16Mar2021: Added One-Click tool reference.

Another month, another set of security updates for Exchange Server 2016 and 2019, including out-of-band updates for Exchange 2013 CU23 and Exchange 2010 SP3 (Rollup 32). Given the risk of this vulnerability, security updates for older out-of-support CUs (Ex2016 CU8 was released December 2017) were also made available. According to the related Exchange team blo g, these exploits are seen being used as part of an attack chain. After publication of this vulnerability named Hafnium, proof of concept kits were published after which variations started to appear (e.g. DearCry). Needless to say, the security update is critical and deployment should not be postponed – intermediate mitigations (with consequences) are also available.

These fixes address the following Remote Code Execution vulnerabilities:

Exchange 2013/2016/2019
Exchange 2010/2013/2016/2019
- CVE-2021-26857

The exploit can be fixed by security update, or in case of Exchange 2010 SP3 by applying a Rollup, which you can find in the table below per current Exchange version. Microsoft published security updates for older CUs as well on March 8th; these have been added to the table below.

Exchange Build	Download	Build	Article	Supersedes
Exchange 2019 CU8	Download	15.2.792.10	KB5000871	KB4602269
Exchange 2019 CU7	Download	15.2.721.13	KB5000871	KB4602269
Exchange 2016 CU19	Download	15.1.2176.9	KB5000871	KB4602269
Exchange 2016 CU18	Download	15.1.2106.13	KB5000871	KB4602269
Exchange 2013 CU23	Download	15.0.1497.12	KB5000871	KB4593466
Exchange 2010 SP3 RU32	Download	14.3.513.0	KB5000978
Exchange 2019 CU6	Download	15.2.659.12	KB5000871
Exchange 2019 CU5	Download	15.2.595.8	KB5000871
Exchange 2019 CU4	Download	15.2.529.13	KB5000871
Exchange 2019 CU3	Download	15.2.464.15	KB5000871
Exchange 2019 CU2	Download	15.2.397.11	KB5000871
Exchange 2019 CU1	Download	15.2.330.11	KB5000871
Exchange 2019 RTM	Download	15.2.221.18	KB5000871
Exchange 2016 CU17	Download	15.1.2044.13	KB5000871
Exchange 2016 CU16	Download	15.1.1979.8	KB5000871
Exchange 2016 CU15	Download	15.1.1913.12	KB5000871
Exchange 2016 CU14	Download	15.1.1847.12	KB5000871
Exchange 2016 CU13	Download	15.1.1779.8	KB5000871
Exchange 2016 CU12	Download	15.1.1713.10	KB5000871
Exchange 2016 CU11	Download	15.1.1591.18	KB5000871
Exchange 2016 CU10	Download	15.1.1531.12	KB5000871
Exchange 2016 CU9	Download	15.1.1466.16	KB5000871
Exchange 2016 CU8	Download	15.1.1415.10	KB5000871
Exchange 2013 CU22	Download	15.0.1473.6	KB5000871
Exchange 2013 CU21	Download	15.0.1395.12	KB5000871

Notes:

You may not be prompted for a reboot, but one is required.
When manually installing the update use an elevated command prompt, don’t just double-click the .msp. To apply an .msp from an elevated prompt, e.g. msiexec.exe /p <Full Path to File>.
When you need to update to a more current Cumulative Update first, update using an elevated command prompt, e.g. setup.exe /m:upgrade /IAcceptExchangeServerLicenseTerms
Per product group feedback, Exchange 2010 is not vulnerable to the same attack chain as Exchange 2013/2016/2019, hence the Rollup mentioning a single CVE.
When running product levels earlier than the ones patched, i.e. Exchange 2016 CU17, you are at risk. There are no patches for earlier product levels, so you need to update to a recent CU after which you can install the security update.
When installing a recent CU first in order to be able to install the security update, reboot after installing the CU, then install the security update. This prevents issues caused by files being locked or updating files pending replacement during reboot.
When you are significantly behind regarding keeping your Exchange servers up to date, the blog Upgrade Paths for CU’s and .NET might help in determining an update strategy.
The statement to stay up to date with at most CU n-1 is not some random adage; apart from features and fixes, it also allows you to quickly respond to these type of emergencies.
Make sure you have configured proper Anti-Virus/Malware exclusions for Exchange server, as documented here for Exchange 2016/2019. I’ve seen significant delays or even hangs during setup of Cumulative Updates because of paths and processes not being excluded. When running Exchange virtually, any I/O inspection running on top of your hypervisor is also considered anti-virus/malware software, such as Trend Micro Deep Inspection on VMWare.
When deploying CU(n) on top of CU(n-1) when an interim update already has been installed, it is recommended to uninstall the IU prior to deploying CU(n). While it might go through, an abort is likely with mention of detecting an IU (INTERIMUPDATEDETECTED) in Exchange Setup log.
Security Updates are Cumulative Update level specific. You cannot apply the update for Exchange 2016 CU18 to Exchange 2016 CU19. Note that the security update file has the same name for different Cumulative Updates; I would suggest tagging the file name with the CU level, e.g. Exchange2016-CU18-KB5000871-x64-en.msp.
The publication of security updates for some older CUs does not remove the necessity to update and patch with current CUs.

Indicators & Action
You may want to look for signs that your Exchange server might have been compromised (Indicators of Compromise or IOC). The article HAFNIUM targeting Exchange Servers with 0-day exploits explains this process. A tool is available to assist in scanning systems for indicators, the Microsoft Support Emergency Response Tool (MSERT).

There is also official communication to support this update, including steps to remediate issues with updates and steps to perform analysis (many people overlook the recommendation to run the update elevated for some reason). This deck can be found here: March 2021 Exchange Server Security Update – v1.2.65 – EN.pdf (thanks Chris Lehr).

Mitigations
I would also recommend the official follow-up post, which not only has been updated since the original post, but also includes mitigations for organizations which cannot deploy the update yet:

A script to configure IIS rewrite rules to block cookies used in the attack (mitigates CVE-2021-26855).
Disabling UM Services (mitigates CVE-2021-26857).
Disabling ECP application pool (mitigates CVE-2021-27065).
Disabling OAB application pool (addresses CVE-2021-26858).

Needless to say, steps like disabling ECP or OAB impacts client functionality.

MS published a One-Click Microsoft Exchange On-Premises Mitigation Tool for simplified one-click implementation of mitigation measures on Exchange 2013-2019.

Finally
Since some people are discovering artifacts of HAFNIUM dating before Microsoft’s official communication, people have been wondering how long this has been going on. For those interested, Krebson Security has published an article with a concise timeline of the events related to this attack.