All users are on the same post office.
Client: 14.2.0
Abstract: When creating an e-mail the sender goes to a shared address book. Selects the group, and puts them in as a BC:. User places other people in as TO: Only the people in the TO: get message

Two users proxy into a third account (resource) to send out certain messages.
Users will use a shared address book to select from.
Users will add groups in as BC and some individual people as TO:
User will send e-mail and it will show sent with NO errors.
Going into sent, shows the e-mail but shows the recipients as the number that are in the TO: field. (2 instead of 70)
When opening the message it shows correct people in the TO: field. No people/group in the BC field
On a resend: the BC field will show a user called "GroupName" instead of the group icon, details on the group show NO people.

Properties shows no extra people to be delivered to.

Just ran pabonly check against users (three of them, 2 users and one resource)
No change after running PABONLY check.