SRS and autoreply on gmail

One of my users is having a problem with autoreplies to her aliased gmail address being misrouted.

See: Autoreply with SRS for what appears to be a similar problem. There it is attributed to exim's SRS implementation. We do have "Enable Sender Rewriting Scheme (SRS) Support" set to "on" in our exim configuration.

Specifically, my user's real email address is (masked) hername@gmail.com. She has a forwarder on our system. hername@ourdomain.com, which forwards to hername@gmail.com.

She went into gmail and set up an out-of-office autoreply for hername@gmail.com. Immediately she started getting bounces.

An example:

An email came in from herfriend@anotherdomain.com.

The autoreply then was addressed not to herfriend@anotherdomain.com, as intended, but to SRS0=dHczS=4L=anotherdomain.com=herfriend@ourdomain.com, which fails because herfriend@ourdomain.com is an invalid address.

Is this a known issue or a configuration problem on our end?

 

No on SendGrid, etc. I'm trying to get the user to send me headers for an example message. Is there a place I can send it to you off-forum so I don't have to mask anything?

 

Apologies for the delay.

I finally have this information (albeit from a different user, who has a gmail-hosted domain) and can send it to you via private message.

But how do I do that? I can't find the way.

 

Can you tell whether the intended recipient gets the autoreply or not despite the bounce? Based on a couple of cases I've seen, it looks to me as if the autoreply goes through and the bounce is spurious, but it would be nice to confirm.

 

Following up ...

No luck getting an answer from Google. However, a Gmail user suggests that it is the host's responsibility to "unwrap" the original sender's address from the rewritten envelope return address and route it correctly in the event of autoreplies and bounces.

See "best answer" reply here:
productforums.google.com/forum/#!topic/gmail/nLre7BqsbQA;context-place=topicsearchin/gmail/category$3Amanaging-settings-and-mail|sort:relevance|spell:false

"Gmail sends automatic responses to the return address from the SMTP 'envelope.' In this case, it appears that your email host has started changing the return address using something known as "Sender Rewriting Scheme" (SRS), but they didn't fully implement it. SRS is intended to allow mail forwarders to use SPF, but still get forwarded messages delivered. It encodes the original return address in the rewritten address so that automatic responses can be forwarded to the original sender. Your mail host is using SRS, but not forwarding the responses."

The following appear to support that position (although they speak to bounces rather than autoreplies).

SPF: SRS: "If cob@third.com is undeliverable, pobox.com gets the bounce; it unwraps ann@orig.com and forwards the bounce back to her. Note that no escaping is needed."

Pobox Help: SPF, SRS rewriting and how it affects forwarding email: "But, if your ISP rejects the message for another reason, like your account being over quota, we can still reverse the address, and send the bounce message back to the original message sender."

How to set up aliases: "If for some reason the email ends up bouncing, the NDN will be sent back to SRS0+abcd=Cw=yahoo.com=def@srs.messagingengine.com, which we'll get, then unwrap and send back to def@yahoo.com."

If this is correct, it suggests that cPanel's SRS implementation needs to do that unwrapping. What's the best way to make that happen? It strikes me as a bug, since it causes major problems for some users, as opposed to a feature request for new functionality.

 

Done, ticket #8828761.