On 5/9/21 12:53 PM, jonathan.mailing.li...@gmail.com wrote: > > Just on the topic of Digest emails, I got this bounce today. Is it because of > the From: and To: fields or a more fundamental problem? > > Action: failed > Status: 4.0.0 > Remote-MTA: dns; eu-smtp-inbound-1.mimecast.com > Diagnostic-Code: smtp; 451 Open relay not allowed - > https://community.mimecast.com/docs/DOC-1369#451 > > From: listname-requ...@example.co.uk > Subject: Listname Digest, Vol no, Issue 1 > To: listn...@example.co.uk > Reply-To: listn...@example.co.uk > > The Mimecast website states: > > "Both the sender AND recipient domains specified in the transmission are > external to Mimecast, and aren't allowed to relay through the Mimecast > service and / or the connecting IP address isn't recognized as authorized. > Mimecast customers should contact Mimecast Support for add the Authorized > Outbound address, or to take other remedial action."
This has nothing to do with From: and To: headers. The sender AND recipient domains referred to in the above are the domains of the envelope sender and the envelope recipient. These would normally be the domains of the mailman host for the envelope sender and the domain of the recipient of this specific digest for the envelope recipient. I.e., what's happening is this user's address is some_user@some.domain. The DNS MX record (mail exchange server) for some.domain points to eu-smtp-inbound-1.mimecast.com, and that server is saying it can't relay mail to some.domain. This is either a DNS mis-configuration on the part of some.domain which would result in all mail to some_user@some.domain from anywhere outside of mimecast.com to be rejected in this way, or it could be some transient glitch either at mimecast.com or at the sending server. Without seeing the actual recipient domain, I can't say more, but as I said it has nothing at all to do with the From: and To: headers of the mail. -- Mark Sapiro <m...@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan ------------------------------------------------------ Mailman-Users mailing list -- mailman-users@python.org To unsubscribe send an email to mailman-users-le...@python.org https://mail.python.org/mailman3/lists/mailman-users.python.org/ Mailman FAQ: http://wiki.list.org/x/AgA3 Security Policy: http://wiki.list.org/x/QIA9 Searchable Archives: https://www.mail-archive.com/mailman-users@python.org/ https://mail.python.org/archives/list/mailman-users@python.org/
