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In the past two weeks, I've noticed multiple popstate-x.dat folders showing up under my e-mail root folder (IMAP).

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I'm up to popstate-9.dat. I'm assuming these folders used to be hidden (I've been using Thunderbird for many, many years). Why are they showing up now? Can I safely delete them, without triggering the server to resend ALL of the e-mails out there?

My husband and I share the IMAP e-mail account on separate computers, and we're both using Thunderbird. I'm using version 68.3.1.

I'm up to popstate-9.dat. I'm assuming these folders used to be hidden (I've been using Thunderbird for many, many years). Why are they showing up now? Can I safely delete them, without triggering the server to resend ALL of the e-mails out there? My husband and I share the IMAP e-mail account on separate computers, and we're both using Thunderbird. I'm using version 68.3.1.

All Replies (8)

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The popstate files store the record of what's been downloaded in a POP account. They don't exist for IMAP accounts, so they are probably the remnants of a POP account that's been removed or converted to IMAP. TB doesn't remove profile files for an account that is removed, unless you check the box.

http://kb.mozillazine.org/Popstate.dat

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Sorry, I think I got it backwards. It's a POP account that's having the issue. I haven't added or removed any accounts in at least 6 months and haven't touched this one at all.

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I guess I'm trying to understand why I now have 9 popstate.dat folders showing up in Thunderbird. I've never seen them before.

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Here are a couple of references that may apply:

https://support.mozilla.org/en-US/questions/1129690

https://support.mozilla.org/en-US/questions/1200553

It could also be caused by an antivirus app that is scanning the mail folder and locking the .dat file, forcing a new version. Always exclude the profile folder from AV programs; leave the real-time background scanner in place.

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I haven't run any AV software. The only thing installed is whatever is native to Windows 10. It's possible that a Windows update changed how the virus scanner works, but I don't ever see it running. Must be in the background. I'll see what I can figure out.

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This solution seemed to work. Not sure what triggered all the extra popstate.dat files, but I was able to delete them. We will see if any more show up.

https://support.mozilla.org/en-US/questions/1200553

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mcmackme said

I haven't run any AV software. The only thing installed is whatever is native to Windows 10. It's possible that a Windows update changed how the virus scanner works, but I don't ever see it running. Must be in the background. I'll see what I can figure out.

The native W10 AV is Windows Defender. Add the TB profile folder as an Exclusion in WD Virus and threat protection settings. Help/Troubleshooting Information, about:profiles to see the profile location.

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For me - these popstate.dat files have been showing up sine late 2018 (when I first began to see them). I have no problem deleting them but the question is HOW CAN I PREVENT THEM?

I run Zone Alarm as my av/firewall program. I'll look into that also.