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thunderbird freezes on large mailboxes

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I'm working with Thunderbird since it was still NetscapeMail. I see myself as an ambassador for your software as I install/recommend it on a lot of clients/friends their computers. Now some of these clients (the ones with a lot of big mailboxes) often complain about Thunderbird freezing when getting new mail. I can confirm this behavior on my main computer (running Win10x64 and 6 mailboxes and lots of rss feeds). The freezing is happening when new mails come in and the spam controls do their thing... Thunderbird freezes for some seconds and after unfreezes and all goes back to work... This behavior can be quite irritating on some slower computers, there it takes minutes before the application unfreezes. After all, it always does. How can i debug this problem?

I'm working with Thunderbird since it was still NetscapeMail. I see myself as an ambassador for your software as I install/recommend it on a lot of clients/friends their computers. Now some of these clients (the ones with a lot of big mailboxes) often complain about Thunderbird freezing when getting new mail. I can confirm this behavior on my main computer (running Win10x64 and 6 mailboxes and lots of rss feeds). The freezing is happening when new mails come in and the spam controls do their thing... Thunderbird freezes for some seconds and after unfreezes and all goes back to work... This behavior can be quite irritating on some slower computers, there it takes minutes before the application unfreezes. After all, it always does. How can i debug this problem?

All Replies (3)

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The two minute no muss no fuss test , without touching messages or folders, is start *Windows'* safe mode with networking enabled - win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

Still In Windows safe mode, start thunderbird in safe mode - https://support.mozilla.org/kb/safe-mode-thunderbird

Does problem go away? - If no, then cause is either: bug in Thunderbird, something (eg a setting, file or folder) in your Thunderbird profile, your mail provider. RSS is another possibility. How many RSS feeds are in use? - If yes (problem went away), then (still in Windows safe mode) ... start Thunderbird normally -- If problem is still gone, then cause is a program loaded during windows startup. Possibilities include: antivirus SW, virus/malware, background downloads such as program updates

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I did some further investigation:

  • the problem did not go away in Windows nor in Thunderbird safe mode (also no anti-virus software is installed except for the default Windows Defender).
  • for rss: disabling the rss feed updates in the account settings did not solve the problem
  • for mail: disabling the "check for new mails" options does temporarily solve the issue!

but when manually checking for new messages Thunderbird freezes again in some cases, not every time. I have a feeling it has something to do with the spam filters cause the problem occurs when spam mails are detected by Thunderbird. How can I debug the spam filters? I use SpamAssasin (included in Thunderbird). Are there more spam moving routines?

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Mine seems to be on permahold. It has just happened in the past couple of weeks but is most annoying. Until yesterday, my only anti-virus software was Windows Defender. I added malwarebytes yesterday afternoon. No improvement.