Target mail address in bcc header is not detected for incoming mail

Use case: Incoming mail should be copied into a discourse topic through bcc. DIscourse receives this mail from the mailserver through pop3.

The mailserver has a recipient_bcc_maps table (see http://www.postfix.org/postconf.5.html#recipient_bcc_maps) which adds a bcc header with a discourse+extension target address.

But the incoming mail is rejected by current Discourse 3.5.0.beta1-dev with error msg

Email::Receiver::BadDestinationAddress](https://forum.netzwissen.de/admin/email/rejected)

It looks as if Discourse only reads the to and/or cc. fields, but not bcc. Therefore it does not detect the correct discourse+extension address.

See also old topic Email with correct incoming email address in bcc is being rejected

It should check bcc header as per

Mind sending me the raw email via PM (PII removed is better) so that I can check it?