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IMAP mailbox file is 100x larger than actual email on IMAP server

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  • Last reply by Tom

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Local Dovecot server (2.3.21) macOS 11.7.10 Thunderbird 115.6.1 (64-bit)

On of my Thunderbird mail folders is showing at 100 GB in size in the file system. The actual online IMAP server folder size is less than 1 GB in size, a locally stored Maildir. And Thunderbird shows the mailbox size as 721 MB.

I've search online and in the forum but haven't been able to root out the problem; nor have I been able to find anyone else even having this problem.

The first this I tried was to compact that specific folder but this didn't make a dent.

One thing that I did notice is that when I "type" the various files in Thunderbird's "profile" directory, they return different file types. This seems odd to me as I would expect all of the files to be ASCII only. Here's a sample of three:

  • Problem file (100 GB): Library/Thunderbird/profiles/lsdgt05u.default-release/ImapMail/.localhost/********: UTF-8 Unicode text, with very long lines, with CRLF, LF line terminators
  • HTML? Library/Thunderbird/profiles/lsdgt05u.default-release/ImapMail/.localhost/********: HTML document text, ISO-8859 text, with very long lines, with CRLF, LF line terminators
  • This is what I'd expect: Library/Thunderbird/profiles/lsdgt05u.default-release/ImapMail/.localhost/********: ASCII text, with very long lines, with CRLF, LF line terminators

What might I do to determine why this is happening and how I might to remedy it?

Local Dovecot server (2.3.21) macOS 11.7.10 Thunderbird 115.6.1 (64-bit) On of my Thunderbird mail folders is showing at 100 GB in size in the file system. The actual online IMAP server folder size is less than 1 GB in size, a locally stored Maildir. And Thunderbird shows the mailbox size as 721 MB. I've search online and in the forum but haven't been able to root out the problem; nor have I been able to find anyone else even having this problem. The first this I tried was to compact that specific folder but this didn't make a dent. One thing that I did notice is that when I "type" the various files in Thunderbird's "profile" directory, they return different file types. This seems odd to me as I would expect all of the files to be ASCII only. Here's a sample of three: * Problem file (100 GB): Library/Thunderbird/profiles/lsdgt05u.default-release/ImapMail/.localhost/********: UTF-8 Unicode text, with very long lines, with CRLF, LF line terminators * HTML? Library/Thunderbird/profiles/lsdgt05u.default-release/ImapMail/.localhost/********: HTML document text, ISO-8859 text, with very long lines, with CRLF, LF line terminators * This is what I'd expect: Library/Thunderbird/profiles/lsdgt05u.default-release/ImapMail/.localhost/********: ASCII text, with very long lines, with CRLF, LF line terminators What might I do to determine why this is happening and how I might to remedy it?

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Another thing that's odd... At the bottom of that mailbox folder there were 6 or so messages with nothing but what looked like Chinese characters--not random symbols, but actual text. There were also a couple of emails at the bottom that showed now data in the message view (such as the summary information when looking through the list of emails) and the email bodies showed the source of the email. I looked at about a dozen other emails in the list of 22,000 or so emails and they all looked fine, except for the last half dozen or so.

I checked this behavior against Mail.app's view of the end of that mailbox folder and none of those peculiarities were present.

I'd really love to switch to Thunderbird permanently but I need to understand this problem before I can commit to that. :)

If there's anything that I can provide you to aide in figuring this out, please let me know and I'll provide what I can.

Also note that I had to remove the IMAP account--it was causing me to run quite low on disk space. I can add it back once I have some troubleshooting information to work with.

Please advise as to where I should start to debug this problem. Thanks for any input you can offer.