Below is a list of Exchange versions and related schema versions.

Forest
For the forest, you can find out the current schema version by consulting the rangeUpper property of CN=ms-Exch-Schema-Version-Pt,cn=schema,cn=configuration,<Forest DN>.

To read the forest version, consult the objectVersion property of cn=<ExOrg>,cn=Microsoft Exchange,cn=Services,cn=Configuration,<Forest DN>.

For example, to find out the current Exchange forest schema version, use a tool like ADSIEDIT or dsquery, e.g.

dsquery * CN=ms-Exch-Schema-Version-Pt,cn=schema,cn=configuration,<Forest DN> -scope base –attr rangeUpper

Note that the values of these two properties do not always match for matching schema versions. Also, before Exchange 2003 objectVersion didn’t exist so you need to query rangeUpper in that case.

Domain
Besides the forest schema version there’s also a domain schema version (i.e. ForestPrep versus DomainPrep). To find out the schema version of the domain, query the objectVersion property in the Microsoft Exchange System Objects container of the <Domain NC>.

Versions