Members are not being enumerated by the QMM for Exchange tool such that they can be added to a collection.
The HomeMTA attribute on the source user(s) may be missing.
Check and ensure the HomeMTA attribute is populated with an adequate HomeMTA attribute.
One method of getting the system to populate this attribute on user accounts:
The MSA uses this attribute to determine which group members belong in a particular collection. Correct the issue by moving the mailboxes to a different database, which automatically fills in the missing homeMTA attribute, and then re-add the source organization. Once complete the users should be enumerated and can be added to a collection.
