What is your anti-virus software?

WIndows defender and Malwarebytes. Exempting a mail client from scanning is not a solution and not an acceptable work around. Other mail clients do not constantly freeze up because of anti-virus processes.

A common problem with Thunderbird

Try to start Windows in 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

Does the problem go away?

If so, the suggestion would be to create an exception for the real-time scannner to scan the Thunderbird profile folder. http://kb.mozillazine.org/Profile_folder_-_Thunderbird

This doesn't make you less secure in any way. It is of course up to you to follow the suggestion or not.

I assume that you are referring to: %APPDATA%\Thunderbird\Profiles

Why is OK to exclude the folder from scanning?

And why can't the underlying problem that causes the freeze ups when the folder is being scan just be corrected?

Other mail clients don't have this problem. I view it as an unacceptable work around that potentially creates a security hole. I would appreciate an explanation of why "This doesn't make you less secure in any way."

Non mi spuntano le domande

Non spuntano le domande

blogman said

I assume that you are referring to: %APPDATA%\Thunderbird\Profiles Why is OK to exclude the folder from scanning? And why can't the underlying problem that causes the freeze ups when the folder is being scan just be corrected? Other mail clients don't have this problem. I view it as an unacceptable work around that potentially creates a security hole. I would appreciate an explanation of why "This doesn't make you less secure in any way."

I would appreciate an explanation of why "This doesn't make you less secure in any way."

These links should give you a good start. Beyond that you can do your own research. http://thundercloud.net/infoave/tutorials/email-scanning/ https://thunderbirdtweaks.blogspot.com/2011/07/anti-virusfirewall-programs.html https://thunderbirdtweaks.blogspot.com/2017/01/anti-virus-again.html

So basically the answer is that it is OK to exclude mail folders from scanning because anti-virus programs are ineffective anyhow. While that hardly surprises me, the fact is that they are not completely ineffective. And the answer does not address the other part of the question. The other mail clients don't seem to have this problem so why can't whatever is causing the freeze-ups just be fixed? What is so different about Thunderbird that it has to freeze up because the profile folder is being scanned when the analogous folders and files in other mail clients can be scanned without anywhere near as drastic a failure? Remember, most people aren't privy to the arcane explanation that anti-virus software is wholly inadequate and many that are probably don't believe that, even if it is true, that such inadequacy justifies leaving holes in what security there is.

blogman said

So basically the answer is that it is OK to exclude mail folders from scanning because anti-virus programs are ineffective anyhow.

No. It is Ok to exclude mail folders because your email is plain text. Even if that mime encoded version of your mail has the worse virus on the planet it can do exactly nothing unless it is converted to an executable form and exectuted. To do that Thunderbird has to write the ting to your systems temp folder. If your anti virus program allows the write and execute to complete without an issue, then your anti virus is the problem.

While that hardly surprises me, the fact is that they are not completely ineffective. And the answer does not address the other part of the question. The other mail clients don't seem to have this problem so why can't whatever is causing the freeze-ups just be fixed? What is so different about Thunderbird that it has to freeze up because the profile folder is being scanned when the analogous folders and files in other mail clients can be scanned without anywhere near as drastic a failure?

You are drawing a low bow there. Why does an oil tanker burn more diesel that a motor car. They both move people from place to place. Thunderbirds storage structure is completely different to say Outlook. What your mail looks like on the local hard disk, or if it is there at all depend on the software, so just because you have the same email on 4 or 5 different You will also probably find anti virus product do not scan PST/OST files. They rely on their outlook add-on. Makes being a Microsoft Partner much easier if you do not break their software.

Anti virus vendors are becoming increasingly aggressive in the files they scan. Historically they scanned executable files. So unless the file met a list of "executable" file extensions or mime types it was not scanned. Now they tend to scan everything they can find because their detection heuristics and basically not as reliable as the once were.

The scanning process is slow. Very slow. It is not uncommon for Thunderbird to have files in excess of a Gigabyte in size. It is also not uncommon for anti virus programs to take 10 minutes to scan a file of that size. You get mail and move it from one folder to the next. That is 30 minutes of scanning. 10 for getting the mail. 10 for removing the mail from the inbox and 10 for adding it to the folder you dropped it into.

If you want to scan your mail there is a setting in options > security > anti virus to allow the scanning of mail that impacts the Thunderbird profile folders not at all. The only caveat is you get messages about files being missing when the anti virus quarantines the incoming mail.

Remember, most people aren't privy to the arcane explanation that anti-virus software is wholly inadequate and many that are probably don't believe that, even if it is true, that such inadequacy justifies leaving holes in what security there is.

That last statement looks like a very good bit of advice. If you work for an anti virus vendor. I have to also remember that most folks are proud of the fact they are "not technical" and "not geeks". Unfortunately I can do no more to counter ignorance than I attempt to do now. It is an impossible task. Folks would much rather parrot slick advertising that actually engage their brain. If you doubt that, spend a few minutes on social media where apparently normal folks start uttering complete rubbish.

I would dearly love to fix the problem. But somehow most folk would complain I think if we arbitrarily removed their anti virus program. We have considered putting up warning when Thunderbird is installed notifying owners of certain anti virus products that their experience will be degraded. However I think litigation might ensure from Nortons, Avast, Kaspersky and McAfee. as they are the prime examples of product that will make Thunderbird crawl along or stop responding or just stop receiving mail entirely.

In a computing era where local storage of personal data is minuscule in most cases with folk relying on some cloud provider to manage their data. Thunderbird has huge local storage. In many cases 3 or more times the size of the actual mail stored in Thunderbird.

There is an innocuous prompt when Thunderbird is first installed offering to allow Windows search to index your mail. It does not say there that allowing this will cause an email like file to be written into the hard disk so the windows search can do the indexing. so suddenly your 10,000 email are duplicated. Or the first 20kb of them is.

Simply turning off the allow windows search (options > Advanced> General) can speed u the whole show. When I turned the option off I deleted manually from my profile folder over 100,000 wdseml files. Like everyone else, when I started using Thunderbird I had no idea what I was doing with these things. I had to learn. I never use windows search. that siri like thing drives me insane.

Another bottleneck is Thunderbirds global search. It is a database. On my system this is many GB in size. Turning it off saved overheads and offers less for an anti virus to choke on. But it makes searching mail much more difficult.