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Sending out mail passes SPF and e-mail comes from x.x.x.207. However, if an out of office message is setup (Outlook client, 2016), the autoresponse then fails SPF and comes from x.x.x.213 instead with the message: x.x.x.213: mailouts.'OurISP'.co.uk does not designate permitted sender hosts.

I've then tested adding ip4:x.x.x.213 and include:mailouts.'OurISP'.co.uk into our SPF but still getting the same message. I am unsure why this error message is still occurring after I've literally said 'I allow x.x.x.213 as a permitted sender', if anyone can advise please?

Also, after contacting the ISP, They were unable to advise why it was coming under a different IP but Im assuming it's because the return path is null (<>) and this may be a trigger for spam-like material (and hence why this particular relay is used). They amended the SPF to use a PTR lookup which did not work either.

edit: the issue is that the out of office messages are going into spam. All other mail is working fine.

Thanks

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This is a common problem with redirected mails, including auto responses. If the system to which one the message was directed to has an account for this user and if a shell is available to this user, the user can get the message, then generates a new one which is the response and sends it from the system where the shell is running. In this way, no message is redirected. A new one is generated.

This solution has drawbacks. If the new message cannot reach its recipient, the error message will only be sent to the shell user, not to the user which has sent the original message.

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  • Thank you for your response Claude. Just to clarify, is this a shell we would use on our end, within the business? Context is: Customer of the business e-mails in, they receive an autoresponse because this person is on holiday, for example. End result being the customer received the autoresponse into their inbox (and not junk)
    – RhysPickett
    Mar 18, 2019 at 16:06
  • It should be a shell allowing the execution of commands. bash or csh or zsh for example. If such a shell is not available to the user, then the proposed solution doesn't work.
    – Claude Frantz
    Mar 18, 2019 at 16:11
  • I understand. The users will have access to a shell if this is the only way. Feels a bit brute force, but the issue cannot be ignored as people are missing the autoreponse and are thinking we are ignoring them. Thanks again for your response
    – RhysPickett
    Mar 18, 2019 at 16:24
  • It's not brute force. But on systems which are only handling E-Mail and which have only special mail accounts for the user, the proposed solution cannot work.
    – Claude Frantz
    Mar 18, 2019 at 16:48
  • It's not brute force. But on systems which are only handling E-Mail and which have only special mail accounts for the user, the proposed solution cannot work. The problem occurs with SPF because the response message is sent from a system where the recipient of the first message is not allowed to send from, according to SPF. Only when SPF is disabled, this can work. But disabling SPF is really a bad idea today.
    – Claude Frantz
    Mar 18, 2019 at 16:55

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