Maximum length of MAIL FROM address

Question

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?

Community · Accepted Answer · 2017-05-23 12:41:08Z

6

Accoding to the answers given at

The answer is 254 according to RFC 5321

So, those MTA are badly configured.

CommunityBot

1

answered Jun 4, 2014 at 14:03

TomTom

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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, 2014 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, 2014 at 14:30

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