Try adding the setting PageSize="1000" to your query parameters. For example:
<ActiveDirectoryQuery><Directives WhereToBind="LDAP://CN=Users, DC=test, DC=com" Filter="(objectCategory=user)" SearchScope="onelevel" PropertiesToReturn="cn" PageSize="1000"/></ActiveDirectoryQuery>
By default Active Directory only allows for a single page of 1000 results. By explicitly setting this value multiple pages (and hence all results) are returned.
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After installing ActiveADAPTER you will see a new transport type option when configuring a send port or receive location. With BizTalk send ports, you can create, delete, rename, move, and modify Active Directory objects. With BizTalk receive locations, you can draw XML messages into BizTalk containing Active Directory query results.

On your Programs menu you will also have an ActiveADAPTER program group containing shortcuts to documentation, sample orchestrations and schemas to get you developing your solutions quickly.
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