For any readers, this basic grep is good enough to cull out the positive messages to hunt for bad looking stuff:
grep MDN *.log | grep -Ev "(Successfully sent MDN|Sending MDNs|is an MDN)"
On my end, the data is clear (a random error once every few weeks). But on his end, yeah we have a problem Houston - hundreds of log lines like this:
2026-05-22-08-04-29.log:2026-05-27T00:30:24.299Z core/event WARNING "" 1 "src/mimeparser.rs:2417: Ignoring MDN sent to self, this is a bug on the sender device."
2026-05-22-08-04-29.log:2026-05-27T00:30:24.300Z core/event WARNING "" 1 "src/mimeparser.rs:2417: Ignoring MDN sent to self, this is a bug on the sender device."
2026-05-22-08-04-29.log:2026-05-27T00:30:24.321Z core/event WARNING "" 1 "src/mimeparser.rs:2417: Ignoring MDN sent to self, this is a bug on the sender device."
The logs on his end are from the macOS Deltachat Desktop client. That surely doesn’t look good… other than those (90% of the log) we see 2 other random errors:
INFO "" 1 "src/mimeparser.rs:2457: Ignoring MDN, found no message with Message-ID
This is back in March, and I had a few of these “back then” too. Ignoring, not important but this one other that only rarely shows up:
INFO "" 1 "src/smtp.rs:482: Ratelimiter does not allow sending MDNs now."
…but that was last logged a month ago. It’s the first set of log lines about sending MDN to self, they’re repeated by the hundreds in his logs.