Allow list entries not working with Bounce Address Tag Validation (BATV) senders.
First seen in
PureMessage for Microsoft Exchange
Emails from a BATV account have a different envelope sender than the actual sender address to stop illegal NDR reports from flooding the senders email server by specifying a unique envelope sender address for each email, for example:
PureMessage uses the envelope sender address to ascertain the sender, this means adding just the recipient's email address to the Allow list will not work when BATV is used by the sender.
What To Do
As the envelope sender address is unique for each email you will have to adjust the format in which you add the Allow list exclusion. PureMessage supports the use of wild cards and you can add the user to the white list by specifying their address in the below format.
The wildcard symbol (*) denotes an entry of any number of characters before the email address.