This is common with Yahoo mail as they repeatedly scan all mail folders and move mail back to their junk folder.

My understanding is there has recently been identified a bug in Thunderbird which results in Thunderbird not removing a spam flag when mail is marked as not spam in Thunderbird, so I guess you need to mark it as not spam in your providers web service unti the bug is fixed.

Matt said

This is common with Yahoo mail as they repeatedly scan all mail folders and move mail back to their junk folder. My understanding is there has recently been identified a bug in Thunderbird which results in Thunderbird not removing a spam flag when mail is marked as not spam in Thunderbird, so I guess you need to mark it as not spam in your providers web service unti the bug is fixed.

Thanks for the reply. None of my accounts are served by Yahoo. The account in question is served by shaw.ca. Funny enough, your support message was treated as junk, so I'm replying from the junk folder ....  :) My other accounts are through gmail and they don't have the problem. Although this never used to happen before with any account and I've used TB for years.

Anyway, I hope the identified bug can be fixed soon. Thanks

I certainly see no issues with Gmail, I am not a shaw customer, but my understanding is they use Microsoft services not Yahoo. So the bug in question should not be affecting you.

Just did a not junk on a gmail account mail did not return to the spam folder.

Perhaps try the following;

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.

Matt said

I certainly see no issues with Gmail, I am not a shaw customer, but my understanding is they use Microsoft services not Yahoo. So the bug in question should not be affecting you. Just did a not junk on a gmail account mail did not return to the spam folder. Perhaps try the following;

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.

I need to apologize for wasting your time ... I just realized that I had a mail filter that despite working as intended as junk filter for certain type of messages that the built in junk algorithm was unable to detect, it was also sending to the junk folder a few other messages that were also meeting the conditions. I modified the filter and everything seems to be ok. Thanks for your help.

I have the same problem. TB is marking non-junk e-mails as junk. I mark them Not Junk and TB changes it right back to junk. I am not using Yahoo or shaw. I restarted TB with all add-ons disabled. Nothing helps - TB still does the same thing - junk, non-junk, back to junk. My "providers web service" does not mark these e-mail as junk/spam - this only happens after the e-mails are downloaded into TB. I have posted this problem at least 2 times with no reply and no solution.