Re: Email rejection #smtp510

Jeff Coleman


It is quite straightforward to post a message to your list every now and again.


“If you wish to reply to the sender off-list, rather than to the whole list, make sure that any = sign in the apparent email address of the sender is replaced by @”


A quick sampling of recent messages I have received on suggests that the replacement of @ by = in senders’ email addresses seems to occur when the email provider is based in UK, such as btinternet and btopenworld, but this may not be a general rule.





From: <> On Behalf Of Malcolm Austen
Sent: 19 February 2021 12:34
Subject: [GMF] Email rejection #smtp510


I have a subscriber this morning reporting that he cannot reply to sender. That is to say that when he replies he gets an smtp 510 error report sent back.


I will continue to scan for old instances in the archives but just in case this is a newly arisen overnight error ...


This is an AOL customer trying to reply directly to a 'munged' address and getting back:


-----Original Message-----

Sent: Fri, 19 Feb 2021 11:23

Subject: Failure Notice


Sorry, we were unable to deliver your message to the following address.


510: The group '' does not exist. You are subscribed to the following groups:


My observations on this:

  1. That email (which is what sent out as the from address) should be forwarded to <bbbbbb@...>.
  2. '=' is a valid character in a group name, so how does decide whether to forward outwards or submit into a group?
  3. Maybe it's an AOL issue but I can't (yet?) see how.




Malcolm Austen <malcolm.austen@...>

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