Anti-virus software is known to cause corruption of Thunderbird mail files. Create an exception in your anti-virus software for the Thunderbird profile folder, so that the anti-virus real-time scanner will not scan it. https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#w_how-to-find-your-profile

I have 2 different emails the one in question and (customerservice@wiegandsportsusa.com) that are on Thunderbird. The other is fine and not having the problem but the wiegandservices one is so it is not related to the virus software. It is something else that is causing the issue.

Not only do I get blank emails my emails also get all mixed up. The information in one email will come up in a different email even though there is no connection or reason why it should. Also when I open some of them all I get is code. So it is a lot of different errors. I have to constantly repair the folder. If I only have a couple emails in the folder it isn't bad but once I start to get past 20 or so it is terrible. As previously mentioned it is only my services email and not my other one even though both are being opened and read in the same Thunderbird app at the same time. My understanding is it is a mapping error on the server.

I have to constantly repair the folder.

And what do you think why you have to do that frequently? Something is corrupting Thunderbird mail files. This corruption is local, and has got nothing to do with the server. The most like cause for corruption is anti-virus software.

My understanding is it is a mapping error on the server.

Log on to your account via webmail, and check whether there are blank messages too. I doubt it.

The other is fine and not having the problem but the wiegandservices one is so it is not related to the virus software. It is something else that is causing the issue.

Since you already concluded anti-virus isn't the problem, I can't help you. Good luck.

My environment is: thunderbir updated running on w10 wit ESET endpoint security, IMAP connecting to remote linux vps mail servers (qmail,dovecot)

In my case, I see the effect exposed by customerservice20 in some account on some customers PCs. In those cases the effect is not so severe, only affects to isolated emails or groups of 3-10 emails downloaded in a period of time , minutes or hours. Te smallest of those inbox are around 2k emails, the biggest 15k, but there are other bigger inbox at the same customers with no problems reported.

I see obvious that there happen corruption in the email storage, the question is why. By now the temporal patch is repair the folder. In big inbox I move the corrupted emails to a temporal folder and repair this one, to avoid downloading several GBs.

In my case this started happening few months ago. I have sent a ticket to the antivirus support team, waiting for an answer.

It wold be great to include a tool to force re-download an email or a group of them.

P.D: thunderbird is the best desktop email client by far. thanks a lot.