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Email bounce error messages

These are some common email errors, reasons for getting them and possible solutions.

550-5.7.25 The IP address sending this message does not have a PTR

  • Source: (or gmail provided domain)
  • Explanation: This is due to a recent change by google and happens when an email is sent from a gmail address to an MIT mailing list that also contains a gmail address. Any gmail address on that list will generate the above error message.
  • Solution: If you need to send to a list containing gmail addresses, please send from your account.

554 5.7.1 Message contained too many MIME parts. We do not accept such complicated messages.

  • Source:
  • Explanation: We believe this error message is part of MIT's spam filtering since some spammers attach dozens of images to email in an attempt to evade filtering. It happens if the email contains more than about 20 mime parts. Unfortunately, it can block people from receiving legitimate MIME-formatted digests of mailing lists.
  • Solution: send simpler messages with fewer MIME parts. If you are signed up to receive a MIME-formatted mailing list digest, get off the digest and switch to direct delivery of individual messages. You can use email filters to send those messages to a sub-folder of your inbox to avoid your inbox being overloaded by those messages.

553 5.0.0 <>... Config error.

  • Source:
  • Explanation: This message comes from It is an access restriction. only accepts email whose "From" address is an "" address.
  • Solution: Go into the preferences/options for your email program, and configure your "From" address to end in "".

550 5.7.1 <>... Relaying denied.

  • Source:
  • Explanation: you can get this message if you connect to one of the incoming MX hosts, and attempt to submit a message that addressed to the outside world – anything that is not a recipient.
  • Solution: outgoing mail should be sent via, not via

550 5.7.1 Bobo with your canned meat?

  • Source:
  • Explanation: This is a poorly-worded error that means, for some reason or another, thought your mail looked like spam, and refused to accept it. It is hard to describe further, because this error text has been used for multiple troublesome situations.
  • Solution: speak to an email expert at the computing helpdesk for further guidance.

451 4.3.0 Bobo with your canned meat?

  • Source:
  • Explanation: This indicates that the MIT server is concerned that the mail might be spam. It is associated with a rate limit. If you send too many messages the emails servers become concerned your account may have been compromised by a spammer and you can start getting this. For further information, see Why am I getting a Bobo with your canned meat email error message?

554 5.7.1 Bobo with your canned meat?

  • Source:
  • Explanation: This may mean your Moira account is status Deleted (3) and you aren't permitted to use the username/password of a deactivated user.

IS&T Contributions

Documentation and information provided by IS&T staff members

Last Modified:

July 27, 2022

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