get-csaduser -filter {Enabled -ne $True} -OU "ou=orgunit,dc=domain,dc=topleveldomain"| sort SamAccountName |ft SamAccountName, UserPrincipalName
Lists users contained in the specified organizational unit that are not enabled for Lync in a table ordered by username (ascending).
Useful for finding users not listed in Lync Server Control Panel. The reason for this is most likely that the user has an AD primary email address (UserPrincipalName) in a domain that is not Sip enabled.
This can happen if your AD domain is not the same as your sip/e-mail domain. To correct this, you could either change the primary email address in AD(best option) and try again when AD is synced, or you could manually specify a sip address in the correct domain (Enable-CSUser –SipAddress “sip:x@y.tld” …)