sounds like anti virus problems. What happens if you disable email scanning?

I use Gdata antivirus. Disabling didn't help. After a few hours, the mails came in. The rest of the week all mails got in. After one week, I got the same problem. From 13 mails only the first 6 came in. It took hours for the others to come in. TB is also very slow in reacting on commands. opening and deleting mails takes quite some time. I've got the same problem when I was using Eudora Ose. First it ran smooth, after some time it got very slow. I decided to switch over to TB. at first it ran smooth, but now it getting very, very slow. No change in virus software etc. So if anyone recognises the problem and know the solution, I would be grateful.

Still sounds like anti virus to me. Especially the slowness part. As your profile gets bigger your anti virus takes longer to interfere in every file open and close

Excluding the Thunderbird profile folder from anti virus scanning "on access" is an approach that has worked for many.

Try restarting your operating system in Safe mode with networking and see if that provides any positive benefit. Windows 7,

I had the same issue, also using GData. After desactivating different parts of GData, I realised that it's related to the "Real time protection".

I managed to desactivate those slowness, but adding an exception to the Real Time protection. The exception being, the thunderbird data.

For instance, for me it was : C:\Users\Jeremy\AppData\Roaming\Thunderbird\Profiles

I think you are right that antivirus slows down the process. When I disable email scanning, emails come in where they first were not retrieved. The funny thing is, that it's an intermittent problem, at times they come in without problem.

@Matt I can't run TB in safe mode as the mail resides at a different encrypted disk and encryption doesn't work in safe mode.

@herbertwest I created the exception on the profile folder, but no improvement. I also don't want to disable the email scanning, as I receive regularly viruses through spam. So I have to live with this problem? (or switch to a faster antivirus)

The encryption itself could be a cause of slowness. But how exactly does a virus received in Thunderbird affect your computer is my main question.

There is no Javascript or VBSript or any other sort of script. Remote images are blocked, attachments are just so much cord wood until you open them. Your anti virus I am sure will proudly claim to catch any virus you try and execute from say a USB stick. Opening an attachment is exactly the same as opening that same file from a USB stick. So what is email scanning doing that is worth it being slow?

Other programs are not (noticable ) bothered by the encryprion, so I rule this out. So you say, that receiving mail and opening and deleting mail will not trigger any virus coming in through mail? So I can skip scanning incoming mail? Ok that will solve my problem.

Remains the question why I suddenly have this slowness problem, when it was functioning fine before. It didn't degrade gradually, but it happened overnight. Anyway thanks for your support.

Again what changed at the time? The most regular thing to change on all our Windows computers is the anti virus. Daily updates or more frequent is the norm. Prior information on what they contain, most unusual. There is usually a log of updates, that is how i found mine had updated itself program updater and definitions, all in one day.