Avast is blocking IMAP email access in Mozilla Thunderbird

[Shaun985]

I haven't been able to get IMAP emails through Thunderbird on my gmail and outlook accounts for several days.  Thunderbird fails to sync and just shows blank folders or old emails without updating with new ones.  I disabled all shields in Avast and the emails started working again.  I then checked my family's other PCs and sure enough they all had the same problem and all were fixed by disabling all shields in Avast.  Is this some sort of bug and how do I fix it? 

Happens on the following systems (with various different IMAP accounts and operating systems)
Operating Systems: Win 10 Home 64bit build 1909 / Win 7 Pro 64 bit
Client: Mozilla Thunderbird 68.8.1 (also happens with the previous version, 68.8.0)
Avast Free: 20.3.2405 (build 20.3.5200.575) (also happens with the version previous to this one)

[Shaun985]

Also I just tested this again and I can fix the issue by just disabling the Mail Shield and leaving everything else on.

[Asyn]

Follow instructions: https://support.avast.com/article/33/ and post the name of the Support-File here afterwards.

[Shaun985]

Alright I will try and get that done in the morning.  It is happening across multiple PCs so it shouldn't be system specific. 

Here is some more information for you:

In Thunderbird when you click an IMAP account folder like the inbox usually it will say "connecting to imap.gmail.com...." then "connected to imap.gmail.com..." then "sending login information" and "opening folder...."

With Avast Mail shield turned on, it will only get to the "connected to" part.

[HK]

Hi Shaun,

I'm very sorry you are having issues with using thunderbird together with avast.

Could you please help us with the investigation by providing some data?

Please enable debug logging (Menu > Settings > General > Troubleshooting > Enable debug logging)
Reproduce the issue (try to connect to imap.gmail.com).

Create a support package (https://support.avast.com/en-eu/article/Submit-support-file) and post the ID here.

Thank you very much,
HK

[Shaun985]

Well good news!  This morning everything started working, across all PCs.  Not sure if there was a Thunderbird or Windows update or something.  Did Avast fix this?  Strange!

[Shaun985]

Bumping this up since I see others with the same complaints again (such as here: https://forum.avast.com/index.php?topic=235820.0). 

The problem has started again for me and it seems to happen randomly but when it does, it affects all PCs (newest avast version, windows 7, 10 with latest thunderbird).

Seems Avast constantly has issues with the Mail Shield blocking IMAP connections in email clients, and it resolves itself without any explanation after a period of time.

So right now nobody in the house can access their gmail or hotmail accounts through Thunderbird.  Is there a known solution for this?

[Asyn]

See Reply #4 from HK.

[Shaun985]

I followed the instructions and enabled debug logging then tried opening IMAP email in Thunderbird.  Afterwards I tried to send logs but strangely, I do not have the option to "Send Logs" underneath the debug logging setting.

All my Windows 10 PCs are working fine with IMAP Thunderbird right now but all the Windows 7 systems are completely blocked out.  Usually it will say in the Thunderbird status bar "Sending Login Information" etc. etc. so I know it is working but whenever Mail Shield is blocking email it only says "Connecting to IMAP" and times out.  This is with the latest version of Avast / Thunderbird.

[AZBruno]

I have also had periodic problems with Thunderbird and Avast, but for me it's been POP3. I posted about this last month here... https://forum.avast.com/index.php?topic=235483.0.

It is still occurring somewhat infrequently because I staggered the checks on my email accounts so as not to run all at once.

[Shaun985]

For me there are less than 2 or 3 accounts per Thunderbird per person in the household and the problem is always with IMAP.  Even if I check one IMAP account it still just gets stuck on "Connected to imap.xxxxxx.xxxx but never gets to the "Sending login info" part.  POP3 seems to always work for me.

Last time this happened across all machines (Windows 7 and 10), but this time it's Windows 7 machines only.
What's strange is that it randomly fixes itself and then blocks up again which makes checking email very unreliable.  I am 100% certain it is Avast because the problem is fixed immediately if I disable Avast.

I did a search and there have been numerous posts about this over the years.  It'd be nice to know what is causing the problem and if there's an easier fix than just temporarily disabling Avast.
Should I just uninstall the Mail Shield component?  Will the other shields work to protect from email viruses if I do this?

I have tried to enable debugging log / send logs but I don't have the send logs option listed in my Avast settings.

[Asyn]

I have tried to enable debugging log / send logs but I don't have the send logs option listed in my Avast settings.

Update to the latest version (20.6.2420): https://forum.avast.com/index.php?topic=236703.0

[Shaun985]

Yes, I am using the latest version.  20.6.2420 (build 20.6.5495.588)

[Asyn]

Download and run: http://utils.support.tools.avast.com/tools/support/utils/avastsupport.exe
Post the File-ID and/or name of the Support-File here afterwards.

[Shaun985]

Thank you for the help Asyn!  I submitted support files from two different windows 7 machines with File IDs: 3NB9X and A8KUX