2

When sending out emails with a MAIL FROM address > 81 characters I receive bounce messages from some MTAs:

501 Syntax error - Badly formatted address. (in reply to MAIL FROM command)

As soon as I change the MAIL FROM address to <= 81 characters, the MTA accepts my message.
I didn't find any limits in the RFC docs.

Is this expected behaviour or is the recipients' MTA misconfigurated?

6

Accoding to the answers given at

https://stackoverflow.com/questions/386294/what-is-the-maximum-length-of-a-valid-email-address

The answer is 254 according to RFC 5321

So, those MTA are badly configured.

  • That's the length of a valid email address. Maybe it have something to do with the SMTP protocol or a different restriction though? – horen Jun 4 '14 at 14:29
  • 1
    No, it has not. A SMTP server is magically required to actually acccept valid email addresses, or? How else would it work? – TomTom Jun 4 '14 at 14:30

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