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"Unable to write email to mailbox" & "Messages could not be moved/copied because writing to folder failed"

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  • Last reply by Ed

Anthony G
Anthony G
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Hello, Attached are the messages I have been receiving ever since 6 October 2025. I've tried to read about fixing these myself, to no avail. (I mean, I can Read; I just can't fix this.) I've tried to Compact ALL folders individually. But that seemed to do nothing. (Before 6 October, the Thunderbird window would at least "flicker" a little after compact.) Trash is empty. Tried disabling McAfee AntiVirus & Firewall. And, no, this isn't happening because I'm using McAfee; I've been using McAfee since Windows XP and Thunderbird since before it "broke away" from Mozilla. They have, until 6 October, played nice together. I really like Thunderbird so I do not want to find another email client/program/what-have-you. There are LOTS of saved emails that I cannot move/copy to "save space", so...Help? Please?

Thanking you in advance, tonyg

P.S.-I am not computer illiterate. But, slow, easy to follow, non-BIOS changing, step by step directions would be preferred.

Hello, Attached are the messages I have been receiving ever since 6 October 2025. I've tried to read about fixing these myself, to no avail. (I mean, I can Read; I just can't fix this.) I've tried to Compact ALL folders individually. But that seemed to do nothing. (Before 6 October, the Thunderbird window would at least "flicker" a little after compact.) Trash is empty. Tried disabling McAfee AntiVirus & Firewall. And, no, this isn't happening because I'm using McAfee; I've been using McAfee since Windows XP and Thunderbird since before it "broke away" from Mozilla. They have, until 6 October, played nice together. I really like Thunderbird so I do not want to find another email client/program/what-have-you. There are LOTS of saved emails that I cannot move/copy to "save space", so...Help? Please? Thanking you in advance, tonyg P.S.-I am not computer illiterate. But, slow, easy to follow, non-BIOS changing, step by step directions would be preferred.
Attached screenshots

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Ed
Ed
  • Top 25 Contributor
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What version of TB are you using? That bug is supposedly fixed.

TB menu > Help > About Thunderbird

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Ed
Ed
  • Top 25 Contributor
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Actually, it's not that bug. Maybe this?

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Anthony G
Anthony G Question owner
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Hello Ed, I read through the linked message and thought, maybe my friend sending me a bunch of pics did me in. I forwarded them to a diff email/server, deleted them from the TB-linked email server, restarted the computer and...no-same messages.

I don't want to do this but, as a last resort, could I backup EVERYTHING in TB, uninstall TB, reinstall TB and put the Backed up stuff back in? This would b my "nuclear" option.

Thanks again

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Ed
Ed
  • Top 25 Contributor
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Anthony G said
Hello Ed, I read through the linked message and thought, maybe my friend sending me a bunch of pics did me in. I forwarded them to a diff email/server, deleted them from the TB-linked email server, restarted the computer and...no-same messages. I don't want to do this but, as a last resort, could I backup EVERYTHING in TB, uninstall TB, reinstall TB and put the Backed up stuff back in? This would b my "nuclear" option. Thanks again

You'd only have to back up files you've moved to Local Folders. Instead, see what happens with a new profile.

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