hMailServer forum

One of my users hosts his email address on my system but his mailbox on AOL. He likes the AOL webmail interface; has used for for years; and is resistant to change.

I redirect his mail from his vanity address to @aol.com and this works fine for almost all use cases. My sender reputation is sufficient for even solicited bulk mailings to be accepted for delivery.

A problem sometimes arises when an email from someone on an AOL-related domain (i.e. yahoo.com) is sent to the user at the vanity domain. I forward it to @aol.com mailbox, but AOL thinks this must be SPAM because a message from a sender on the related domain shouldn't need to leave Verizon's internal systems to get between sender and recipient. They are on the same “mail organization”. So the redirected message gets rejected.

For the community:

Any thoughts on the how to characterize the message so that this doesn't happen? Is it best to rewrite headers? Maybe "forward as attachment"? Any other ideas?

I think setting RewriteEnvelopeFromWhenForwarding=1 in hMailServer.ini wil help you here (in most circumstances...if the sender has DMARC and reject policy set this won't work is my experience)
Additional SPF, DKIM signing and DMARC on the internal domain could help you to get it through to AOL

Right, so I think the goal is to characterize the message such that the sender validation score is higher, but the benefits of redirection, such as preserving the originating sender identity for easy reply, are preserved.

Maybe you should try it first? RewriteEnvelopeFromWhenForwarding=1 only changes the From Header, 'the From Address stays the same so sending a reply wouldn't be a issue

I think you mean it changes the MAIL verb, FROM: noun in the envelope to reflect the address the email was forwarded from. The originating sender's email address remains preserved in the From: header. Right?

yep

RewriteEnvelopeFromWhenForwarding