'All Mail' cannot be compacted

[Haircut]

Two POP gmail accounts and one IMAP account. Everytime I am told to compact I get the following alert from the Imap account:

"The folder 'All Mail' cannot be compacted because another operation is in progress. Please try again later."

The account is a shared support account so emails are cleared from the server quarterly.

[DanRaisch]

Close Thunderbird. Navigate to the profile folder and locate the file allmail.msf in the \ImapMail\imap.gmail.com directory. Restart Thunderbird.

[Haircut]

I got a Bash from the KB instructions. However, I right clicked on All Mail and clicked on "Compress" so we will see if that solves the problem.

As far as I know, All Mail is simply a list of subjects on the Imap server that is retrieved from the server. Why should it need to compacted at all?

[DanRaisch]

clicked on "Compress"

Without intending to be pedantic, compacting and compressing are not the same thing.

As far as I know, All Mail is simply a list of subjects on the Imap server that is retrieved from the server. Why should it need to compacted at all?

Google doesn't use actual folders in its webmail system, it uses labels. That means that each message can have multiple labels, which in turn means that a message may be listed as being in the server "Inbox folder" and also in "AllMail" which is simply the list of all messages for your account on the server. Thunderbird, by default, downloads data from the messages on the server so they can be made available to the user when there is no Internet access. The .msf files are indexes for those downloaded messages and that index can be come corrupted, resulting in error messages such as the one you report here. Compacting is part of Thunderbird's process for maintaining both data integrity and performance and compacting addresses both of those issues.