You are using the Schemus LDAP Synchronization Tool and need it to find dynamic distribution list in your Active Directory created by Microsoft Exchange for use with Email Sync

 To make Schemus see Dynamic Lists, you need to update its Default search filter on the LDAP Search tab within the Schemus configuration from:

  (|(&(objectCategory=person)(objectClass=user))(objectCategory=group))

to:

  (|(&(objectCategory=person)(objectClass=user))(objectCategory=group)(objectCategory=msExchDynamicDistributionList))

This will allow the schemus tool to obtain the email address of the Dynamic Distribution List only for use with Address Registration.