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When I attempt to rapidly delete a sequence of emails in Thunderbird that have arrived in the Inbox using the Delete button on the keyboard, Thunderbird freezes for about 5 full seconds for about 1 out of every 4 emails. The other 3/4 delete immediately.

I also use Nostalgy to allow me to move emails from the Inbox to another folder with the press of a single key, and the exact same problem occurs in that case.

I have run Thunderbird in Safe mode, and disabled my Avast antivirus program's "real-time shields" (including mail shield), and neither has fixed the problem.

Also, I quit Thunderbird & deleted all .msf files, and it did not resolve the problem. I attempted to compact my folders, but absolutely nothing happens when I right-click a folder and select "Compact".

Please note that I regularly synchronize the entire Thunderbird folder to online storage and to other workstations, but I never run Thunderbird simultaneously from multiple workstations.

Please help! This problem is becoming so much of a nuisance that I am seriously investigating other email clients. Thank anyone in advance for any suggestions.

Flimzy
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Dan Nissenbaum
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1 Answers1

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Thunderbird uses a slightly modified version of the mboxrd mailbox format for local mailboxes and POP3 mailboxes. The mbox family of mailbox formats is highly inefficient anyway when it comes to expunging messages from and inserting messages into a mailbox. Expunging requires rewriting the entire file from the expunged message onwards. Inserting means at the very minimum seeking to the end of the file and writing. And that's ignoring the additional operations on the summary database.

Combine this with Thunderbird's normal method of deleting messages from mbox files, which is to set a flag in the X-Mozilla-Status: header and leave the message in the file until it is compacted, and things can become very slow. A mailbox with a large number of deleted messages may appear nearly empty, but operations upon it will be slowed down by all of those deleted messages, because as the mailbox file is written and rewritten all of those deleted messages will continue to be included, until the file is compacted.

The rest of the world, including most of the IMAP servers that you won't see exhibiting these problems, has junked the mbox family of mailbox formats long since, precisely because it is slow and fragile in these ways. Several use some variant on the Maildir format, where expunging a message is as fast as deleting an ordinary file from a directory. Some MUAs use Maildir, too.

Alas, Thunderbird users are stuck with mbox. There have been calls for Thunderbird to employ Maildir since at least 2004, possibly earlier. Unluckily for Thunderbird users, after all these years it still hasn't happened.

JdeBP
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