Are you downloading emails into a pop or imap account? When you filter the email where is it going - into a folder in same account or into another account? If other account - Is the other account a pop or imap or the 'Local Folders' account? Where is the affected folder ?

Can you post an image of the filter so I see whether it's just being copied or moved to or whether it's also being deleted or a tag applied etc ?

In 'Message Filters' click on 'Filter Log' button. Is the Filter Log enabled ? Can you see what it has been filtering ? If no - not enabled then enable it now as it's useful for future reference. If yes, scroll down to the last filtered email that used that filter to put in the affected folder. Post an image of what it says.

Do you download full copies?

If this is an imap account: In Account Settings > Synchronisation & Storage for the account Click on 'Advanced' button Is the 'affected folder' listed ? Has it's checkbox been selected to ensure a full copy download into that folder?

Thank you for answering. >>Are you downloading emails into a pop or imap account? I'm using with pop account.

>>When you filter the email where is it going - into a folder in same account or into another account? Same account.

>>Where is the affected folder ? That pop account.

>>Can you post an image of the filter so I see whether it's just being copied or moved to or whether it's also being deleted or a tag applied etc ? Yes I can. But Filter Message is written in Japanese.

>>Is the Filter Log enabled ? Can you see what it has been filtering ? Yes. It's enabled.

>>Post an image of what it says. I cannnot post an image. Because There's a lot of personal/company information. Here's one of the logs.

[2025/03/18 9:13:35] メッセージに "System@振り分け" フィルターを適用しました。差出人: ******株式会社 <****@******.com> 題名: *********** 日時: 2025/03/18 9:08:37 メッセージを移動しました。メッセージ ID: caf10e38-7963-49b0-bf71-6ff5389c2941@iad4s13mta898.xt.local 移動先: mailbox://******%40*******@192.168.11.***/Inbox/System

I have replaced the asterisks and IP addresses with dummy ones.

>>Do you download full copies? Sorry. I'm not sure about this.

OK so email looks like it comes via Salesforce Marketing Cloud marketing servers Filter using: Filter before junk classification Match all the following From contains <system@email address> Perform these actions Move message to: 'System' folder on mail account name Where 'System' folder is a subfolder to the Inbox

All seems ok at this point - I did wonder if you were moving before or after junk classification. The info supplied answered that query. I notice the email came from a xt.local server and sometimes anti-spam server filters may pick up on emails using a marketing server and mark them as spam.

If you downloaded headers and then server moved or removed email from the server Inbox for some reason, then when selected to open it could not retrieve the rest from server.

It's also possible you have Anti-Virus product scanning incoming mail and maybe it does not like the email, so removed it.

Info also tells me the destination of the move is to a subfolder of the Inbox rather than a normal top level folder in pop account.

Test - do emails open if in the Inbox folder. Please disable that System@sort filter and allow those emails to arrive in Inbox. Are you able to open and read those emails when arriving in Inbox?

>>Do you download full copies? > Sorry. I'm not sure about this.

In 'Account Settings'

• Select 'Server Settings' for the pop account
• Q: Is the checkbox 'Fetch Headers only' selected or not ?
• Q: Is the checkbox selected 'Leave messages on server' ?

Suddenly, I became unable to view emails from a certain date onward. I haven't made any particular changes to the settings.

If I move the emails that cannot be viewed from the System folder to the Inbox, I am able to display them. However, I can no longer move them back to the System folder.

When I disabled the message filter and set the emails to arrive in the Inbox, I was able to view their content.

>>Is the checkbox 'Fetch Headers only' selected or not? No

>>Is the checkbox selected 'Leave messages on server'? Yes

I have an identical (or very similar) problem. I've been travelling with my laptop. On my return home I copied my 'Thunderbird' file (which contains ALL my accumulated e-mails, but nothing else) back onto my desktop. I have been doing this for years with no problem (copy to laptop before going away, copy back on return, delete webmail inbox to prevent downloading duplicates).

It was now that I noticed the apparently blank e-mails. I went back to look at the laptop and found the same e-mails were NOT blank. The version of TB on my laptop is later than that on my desktop. I wonder if the problem has something to do with a recent TB update?

It's not confined to e-mails that have been moved by the filter. Some messages aren't blank, but look as if they might be hex versions of an HTML coded e-mail.

I am having a similar problem that just started today. In my case, when I first opened Tbird, it got an authentication error connecting to the Gmail server. So it didn't download any emails. This was resolved after closing and reopening the app. After downloading from the server, the content would not display. This resolved itself after about 10 minutes. But message download is slow. It took 20 minutes for this to fix itself. I have plenty of bandwidth as my computer is Ethernet-connected to the Xfinity modem. I had no problem accessing Gmail from my browser.

I am having a similar problem that just started today. In my case, when I first opened Tbird, it got an authentication error connecting to the Gmail server. So it didn't download any emails. This was resolved after closing and reopening the app. After downloading from the server, the content would not display. This resolved itself after about 10 minutes. But message download is slow. It took 20 minutes for this to fix itself. I have plenty of bandwidth as my computer is Ethernet-connected to the Xfinity modem. I had no problem accessing Gmail from my browser.

This does not sound like the same issue as person who initially created this question. It's much better to ask your own question because your query is being sent to the person who asked this question in the first place. They may not appreciate responses that are not relevant. When you create a question add some additional info like what OS you use, what version of Thunderbird, whether this is an imap or pop account, what Anti-Virus you use. But first check this - please access Anti-Virus and create an exception to not scan your Thunderbird profile folder because any file that opened is being scanned (used by AV) before Thunderbird can access it to write incoming mail etc. You might want to also switch off scanning incoming/outgoing mail to see if it improves things. Thanks.

Sorry for that. When I first posted, it looked like the same issue. I later saw that it was a timing issue, so I just updated my original post. Thanks for the tip about anti-virus. I've put the profiles folder in the exceptions.