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SRS and autoreply on gmail

Discussion in 'E-mail Discussions' started by rclemings, May 5, 2017.

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  1. rclemings

    rclemings Active Member

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    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?
     
  2. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    Are you using any third-party mail services (e.g. SendGrid) on this system? What does the header look like on the email that's delivered to the Google address (the one that triggers the auto-reply)?

    Thank you.
     
  3. rclemings

    rclemings Active Member

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    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?
     
  4. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    You can send it via a private message, or post it here with the identifying information removed.

    Thank you.
     
  5. rclemings

    rclemings Active Member

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    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.
     
  6. cPanelMichael

    cPanelMichael Forums Analyst
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    Hi @rclemings,

    I sent you a private message so you can simply click reply on the conversation.

    Thanks!
     
  7. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    To update, internal case CPANEL-14114 is open to report a scenario where Gmail's autoresponder feature is unable to automatically respond to messages sent from cPanel servers that match the following conditions:

    1. The message sent to Gmail stems from an email forwarder configured in cPanel with the @gmail address as the destination.
    2. SRS is enabled on the cPanel server.

    I'll monitor this case and update this thread with more information as it becomes available.

    Thank you.
     
  8. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    To update, this behavior was determined to be a product of using SRS when the the remote mail server's autoresponder is configured to respond to the "sender" address instead of the "from" address. The workaround is to disable SRS, or to report the issue to the remote mail server (e.g. Gmail) to determine if it's possible to modify their autoresponder's behavior.

    Thank you.
     
  9. rclemings

    rclemings Active Member

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    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.
     
  10. cPanelMichael

    cPanelMichael Forums Analyst
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    In the previous report of this issue, the message was bounced instead of delivered. However, if Gmail was able to successfully send the automatic response to the "sender address" it detected, then the message may have gone through. You likely will receive a better answer about the exact behavior of that message from Google.

    Thank you.
     
  11. rclemings

    rclemings Active Member

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    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.
     
    #11 rclemings, Aug 27, 2017
    Last edited by a moderator: Aug 27, 2017
  12. cPanelMichael

    cPanelMichael Forums Analyst
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    Could you open a bug report with the information in your last response so we can take a closer look and determine if it's something we could implement?

    Submit A Bug Report

    Thank you.
     
  13. rclemings

    rclemings Active Member

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    Done, ticket #8828761.
     
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