BCC map passing email somehow

MikeA

Hi all,

I have Mailcow setup with Address Rewriting > BCC Maps to forward all incoming mail from Mailcow to my personal Gmail account. This worked fine for a week or so, then I had someone mention that their own mail server was bouncing messages when replying to my emails. Note that they were replying to my custom domain email hosted on Mailcow, but somehow, their bounce emails were from Gmail that contained my personal Gmail address which shouldn’t be publicly seen.

I have the BCC map setup like so:
local destination: myemail@mycustomdomain.com
bcc destination: myemail@gmail.com
bcc type: recipient map
domain: mycustomdomain.com

Any idea why my personal gmail is being used when someone replies to an email with the Mailcow BCC map setup?

faisal

Are you keeping a copy of the email on your mailcow? If not, use recipient maps under address rewriting instead to forward.

MikeA

faisal Yes, I need to retain the original on the Mailcow server as well as forward to external Gmail email.

faisal

What did the bounce say? If Gmail bounced the BCC’d message, then its expected to have your Gmail address in the bounce, even if it was a BCC. That’s how bounces work.

MikeA

Here is how it happened.

Email is sent from Mailcow server to individuals email, this email is also BCC’d to my own personal Gmail via address rewirte. When the individual replies to the email sent from Mailcow, it bounced on their end, and provided my personal Gmail that the original message was BCC’d to.

I will try to reproduce with my own.