It's not what you want to hear, but we've encountered this before and "I remember forgetting the fix". One thing Thunderbird strongly dislikes is configuration changes. If you update the IMAP/SMTP hostnames it can leave remnants in the background which can trip it over. Some legacy clients from our previous business push Thunderbird to its limits, and they tend to find it a touch unreliable if the throughput isn't sufficient. Main problem I remember is the drafts failing to save and some sends failing. Like clockwork though, it tended to let it send if you re-tried 1-2 times after the initial fail, though the drafts never quite saved properly. You've ruled out the client/machine/etc as otherwise I'd suggest the folder configuration. Does the issue persist if the IMAP account is set-up in another email client? Same network, same protocol, new client - same issue? What about crypto? Everything on TLS over the proper port/s, verified to work okay? Nothing running on 143/plain or SSL, etc? How do the logs look? https://wiki.mozilla.org/MailNews:Logging#Generating_a_Protocol_Log Do you have any addons running on her Thunderbird installation? They + TB are up-to-date? Cheers, Luke Thompson Operations Manager The Network Crew Pty Ltd https://thenetworkcrew.com.au On 8/4/22 4:14 pm, Karl Auer wrote:
I run a Mikrotik router as my home router, have done for years. I personally have never had an issue with it. The current one is an hAP ac^3 running 6.47.10 with plenty of free RAM and disk space and virtually zero CPU usage.
However one of my "users", running Thunderbird on Windows, has an ongoing problem using IMAP. When she sends an email, the email is not saved to the (IMAP) "Sent" folder. If she saves a draft, it fails to save to the (IMAP) "Drafts" folder. In both cases the failure comes after a long wait, indicating IMHO a network problem.
This does not happen all the time, but often enough (well more than half the time) to be extremely frustrating. We can discern no commonality between the affected messages - large, small, addressees, attachments etc. Sometimes if she disconnects from the network and then reconnects, the message will work the second time around, but IMHO this is just blind luck.
The thing is, this does NOT happen when she is using the same computer outside our home - on a public network, her phone's hotspot or whatever. Only at home.
I have excluded wifi as the problem; she gets the same issue on a wired connection. I have set up my own IMAP connection (though not as yet with Thunderbird) and cannot replicate the problem. She and I use the same local network, the same email provider and the same connectivity provider (ADSL from iiNet). The link is slow (about 14/0.4), but has been dependable and as I say, I do not have any problem other than with speed.
This has been going on for probably about two years now, getting steadily worse, to the point where she now leaves the house to work (which is a big deal, as it's a 40-minute round trip to a suitable location).
I'm at a bit of a loss as to what it might be, and am asking here to see if anyone has a router-related clue. Or any ideas as to how I might go about troubleshooting this.
Regards, K.