On 25 Sep 2023 12:24 -0600, from rickm...@shaw.ca (Rick Macdonald): > # exim4 -Mvl 1qkOYj-001Hnf-2V > > 2023-09-24 06:50:01 Received from <> H=(timshel) [::1] P=smtp S=2662
::1 is IPv6 localhost. So whatever caused that particular message to be sent is almost certainly local to your system. Good. > 2023-09-25 06:41:16 6595-611-17423-903-rickm=timshel...@mail.turntext.co > R=smarthost T=remote_smtp_smarthost defer (-45) H=shawmail.glb.shawcable.net > [64.59.136.142]: SMTP error from remote mail server after MAIL FROM:<> > SIZE=3752: 451 <> server temporarily unavailable. AUP#MXRT Looks like your ISP's smarthost doesn't want null envelope return addresses. 4xx is supposed to be temporary, but seems to me like they are doing it as a pseudo-permanent-error response. > # exim4 -Mvh 1qkOYj-001Hnf-2V ... > --helo_name timshel > -host_address [::1]:34848 > -interface_address [::1]:25 Again, seems to me like confirmation that the email with that particular ID originated locally on your host, not on the network. Which is good, because it means your SMTP server is likely not being abused as an open relay. > The following address(es) failed: > rickm@localhost > SMTP error: 550 header syntax So something running on your local system almost certainly tried to send mail to either "rickm" or "rickm@localhost", and that triggered queuing the non-delivery notice which you're seeing evidence of in your outgoing mail logs. Do you have something like fetchmail set up in multidrop mode, any forwarding procmail rules, spam filtering, or anything similar, especially ones that would be triggered by something being sent to... > X-Original-To: ri...@timshel.ca I know that fetchmail at least used to have a way to set it up to take the local part from the recipient email address and forward that to the local MTA/MDA for delivery. If usernames don't match exactly, that's an easy way to go astray and potentially cause backscatter, especially if you're also set up to use your ISP's outgoing SMTP server as a smarthost. And from Rick: >> I note that the destination addresses on these messages are of the form: >> >> <6626-879-8427-40-rickm=timshel...@mail.purecuresol.co> Indeed, good catch. -- Michael Kjörling 🔗 https://michael.kjorling.se “Remember when, on the Internet, nobody cared that you were a dog?”
