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Thunderbird hangs when sending mail "attaching imagexxx.jpg"

  • 3 replies
  • 1 has this problem
  • Last reply by Matt

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Thunderbird stops responding for about 1-2 minutes every time i'm sending a mail. It freezes on "attaching imagexxx.jpg" xxx being a random number, even the entire name could be different, but it's always a .jpg file.

I've tried changing my own signature, or not using one at all, issue remains. msf files have been deleted, hardware acceleration has been turned off, i've tried about anything i could find.

Anyone have any idea?

Edit: I'm using version 78.7.1 (32 Bits), but issue has been there since several versions.

Thank you in advance.

Attached screenshots

Modified by florian26

All Replies (3)

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Is your Anti-Virus scanning outgoing mail? Do not disable as this usually invokes the default to be enabled and does not always stop it from intervening.

Test: Start computer in 'Safe mode with Networking', start Thunderbird in Safe Mode -

This ensures no third party is involved. Test sending. If OK Restart Thunderbird as normal and Test sending. If problem then issue is in Thunderbird, maybe an addon etc. If OK, then issue may be your Anti-Virus software. Suggest you make Thunderbird profile exempt from scanning and switch off email scanning for outgoing emails.

Please report back on test results.


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Thank you for your advice.

I tried in Safe Mode, which indeed resulted in no issues. I added several exclusions in our antivirus software (trend micro), this however made no difference. I will try with a complete removal of the antivirus software as a test and i'll get back to you. In the meantime, do you happen to have a list of necessary exclusions? I've already added the entire thunderbird folder, MFL files, appadata folders,...

Edit: I've uninstalled the antivirus software completely and that fixes the issue, i'm not sure what else i need to exclude in order for thunderbird to work properly...

Modified by florian26


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open the windows run dialog. (windows key +R) type %tmp% and press enter the file manager/explorer will open to the system temp folder. It is the copies of the files written to this folder that are the issue. How you get your anti virus to not scan files put there just by Thunderbird, I do not know. Excluding the whole folder is probably not a good idea as that folder is also where any infected file you get as an attachment will also be placed. Perhaps the exception should loo more like an exemption for JPG files.

This information from Bullguard makes it fairly clear that extraneous and sometimes malicious codes can reside in JPG files. But what is not fully expanded on, although stated, is that is only a problem if you already have malware on your machine to interpret the malicious content.


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