Today Microsoft released Update Rollup 2 for Microsoft Exchange Server 2010. RU2 comes 3 months after the release of RU1. The list of included fixes is not as long as with RU1, but RU2 does contain some important additional fixes over RU1:

• 977633 Certain third-party IMAP4 clients cannot connect to Exchange Server 2003 mailboxes through an Exchange Server 2010 CAS server
• 979431 The POP3 service crashes when a user connects to a mailbox through the POP3 protocol and the user is migrated from an Exchange Server 2003 server to an Exchange Server 2010 server
• 979480 Users cannot receive new messages if they access mailboxes that are moved to another Exchange Server 2010 RU1 server by using IMAP4 clients
• 979563 Exchange Server 2010 Push Notifications does not work
• 979566 A 0x85010014 error is generated when linked mailbox users try to synchronize their mailboxes with mobile devices in a CAS-CAS proxying scenario in Exchange Server 2010
• 980261 This fix introduces the supports for Exchange Server 2010 page patching when a “-1022” disk I/O error is generated
• 980262 Event ID 2156 is logged on a computer that is running Exchange Server 2010

The related knowledgebase article (KB979611) can be found here. You can download Exchange 2010 Rollup 2 directly from here.