You likely have pop accounts. Try disabling the setting for getting new messages for some of them.

This is working so far. I'll confirm one way or the other soon. Odd, as I had all email addresses downloading easily on the Windows 10 machine.

with Gratitude, L

No, it is not working yet. I had left two email addresses to download. bp-dcff3255-7323-44e7-b38f-bae840250204 I've now instructed one of those not to download at start-up. I will reboot the whole laptop to see if that changes anything. Anything else to try would be appreciated.

I haven't had a crash today. I don't know which bit of the above strategy has worked for me and my patience does not extend (at the moment) to experimenting to find out what I can add back in. In case it helps others, I currently have one email address which downloads at start and at regular intervals, another that does not download at start and then downloads at 6 minute intervals. There are three more addresses (rarely used) that I download manually. Thunderbird (and Windows 11) is neither in a safe mode nor a trouble shooting mode. I will wait a few days before pressing the 'solved the problem' button.

I'm still baffled concerning why I could download at start and at regular intervals for 5 addresses on a Windows 10 laptop but I can't do the same on this new Windows 11 laptop.

Nope, crashed again. Any ideas? bp-992cd53c-0f14-4976-a498-883e20250206

bp-099cc937-e204-42f0-87d7-d35da0250206

Is there an earlier version of Thunderbird that is still functional that does not have this problem? Where do I find it? bp-fc052fb1-f10b-4641-a789-8fbfa0250207

Perhaps have a look at the bug https://bugzilla.mozilla.org/show_bug.cgi?id=1891962

There appears to be a try build that might fix the issue.

Thanks, Matt. I had seen this but I don't understand it other than to suspect that if I download version thunderbird_esr115 rather than the latest version of Thunderbird, the problem might go away...but I couldn't find that version. Have I understood this correctly? I have programmers in the family; I'll ask next time someone appears. --No idea what a try build is.

Thunderbird hasn't crashed in several days. I am downloading messages manually. Any automatic download results in a crash. This isn't ideal, of course, but is working well enough for me to plod on a bit longer.