What mail provider? does it work better if you set it to check mail every 15 or 20 minutes? Live/Hotmail/Outlook for instance simply rejects login attempts that exceed their 15 minute rule.

Thanks Matt. Provider is Time Warner cable. Will change the time to 20 minutes. Will also call TWC. Have not had a problem until recently. Suspect Windows 10.

Does a web browser other than Edge work?

Matt. I fixed the problem by going back to version 38.1. Must be a bug in 38.2. Thanks for your thoughts.

So how do you go back from 38.2 to 38.1? (And what do you give up by so doing?)

Thunderbird 38.1 : ( A link to a site known to bundle malware removed) Just installed it, will see if it works. I got tired of selecting "Check All Messages," I have two email accounts going and with 38.2 just clicking the Check Messages button was only checking one of them, so heads up. Will try 38.3 when it's out, hope they fix this bug.

We do not recommend downloading Thunderbird from anywhere but Mozilla.

For current versions that is getthunderbird.com For old versions that is http://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/

Funny how folk that download from unofficial channels keep having issues with browser hijacks, malware and viruses. Does it ever occur to those using these services that they are commercial enterprises? They make money from your visit. How do the folk at Filehippo ( Well Known Media Ltd) for instance pay the rent on their offices at 200 Aldersgate Street, London?

To quote herdProtect."Well Known Media Ltd is a software publisher located in London, England in United Kingdom*. Software developed by Well Known Media Ltd has been typically classified as potentially unwanted software. "

Unfortunately, no one of this is going to fix your issue, as no one actually knows what it is. Here we have two people, and only two with an issue. It can not be reproduced by others, How you think some one else is going to fix that I do not know.

EDC109 said

(And what do you give up by so doing?)

Security, for the rest see me earlier post.

Perhaps with multiple folk here standard diagnostic processes will shed light on what is the issue.

To diagnose problems with Thunderbird, try both of 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.
• Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.

I used Filehippo because it showed up early in Google hits; you don't have a handy "Previous Versions" link in your sidebar, just like you don't bother with a "Register" button, instead making newcomers to your site go through that laughably arcane process of asking a question and pretending to not have an answer. Between those two issues I'm not keen on hanging around here much. 38.1 from Filehippo is faithfully checking for new messages so I'm happy. Avast and Malwarebytes didn't scream in horror when I installed it so I think I'm safe for the time being, if I find a PUP in there when I get around to scanning it again maybe I'll uninstall. Or not. Haven't had my search engines hacked or anything blatant so don't care.

Major issues here.

1. It really does not matter is Thunderbird is working or not. You have needlessly exposed yourself to malware, based on the location of the hit in Google. Then you recommend similar reckless behavior to others.

2. The registration on this site is something controlled by Mozilla, not the Thunderbird council. If you have issues with the web site, I suggest you address them with Mozilla. I have been trying for a long time. They are no more interested in my complaints than they are in Thunderbird.

3. Avasts most recent release has all sorts of issues with Thunderbird. It would not suprise me if it was the cause of this issue as well.,

4. Not all malware gets detected as such. Just because your anti virus and other security software does nothing only indicates it is not destructive. The first thing Microsoft did upon purchase of Microsoft Security Essentials was remove malware detection of certain programs. Not because they were not malware, but because their authors sued Microsoft saying that Malware does not have an Ok button to install. Hence the more insidious malware that spies on your internet and reports home is often not identified as you clicked an install button to get it.

Do you drive around in a war zone with the windows down and your head out the car window until someone yells sniper? Your doing exactly that by relying on security software to yell the digital equivalent of "snipper".

So, you have made it clear you have no interest in fixing your issue, You would rather debate the relative merits of a rather dubious web site and defend risky behaviour. I am done here, unless there is someone that actually wants to fix the issue by identifying the cause.

Go to the following Mozilla link. It lists all previous versions. Go down the list and click on the entry dated 18-Nov for version 38.1. Select your OS (win32?). Select language (en-US?). Select TB setup

http://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/