Mail can be exported from TB (ImportExportTools NG) or archived in a 3rd-party app, such as MailStore Home. Keep in mind that deleting mail from an IMAP folder in TB will delete it from the gmail server, so you could move old mail to a new folder created on the gmail site, and then not subscribe to that folder in TB. That keeps the mail on the server, but doesn't download it to TB.

Is the All Mail folder subscribed? It can take up a lot of storage, and is usually omitted. See the All Mail section here.

Thanks sfhowes,

I found this webpage that apparently explains how to do what I want (which is keep a local copy of my gmails in Tbird's profile for one week but store only the email headers for emails older than one week. Store Less Mail Locally With Thunderbird for IMAP link text

Provided I use the following setting: ... Tools > Account settings > Synchronization & Storage > Disk Space > Synchronize the most recent _1_ week

However, even with the 1 week setting for my 4 gmail accounts, the size of my Tbird profile folder does not get smaller than the 29.3 GB that I started with. (Up to today, 3 of my gmail accounts in Tbird were set to Synchronize the most recent _1_ day and only one gmail account in Tbird was set to Synchronize all messages locally regardless of age. I changed that setting to synchronize for 1 week but still no reduction in my Tbird's profile folder size.)

Then I read a post that said old copies of email bodies need to be deleted from the profile and Tbird restarted in order to get rid of them in Tbird's profile.

This involves deleting the mbox and msf files from your Tbird profile folder while Tbird is closed (not running/using the profile folder), then relaunching Tbird. This is the only way that I know of, of deleting previously downloaded offline content from your Tbird profile, which could significantly reduce disk space usage by your Tbird profile. My Tbird profile is a mere 85MB and has 7 IMAP accounts on it! Last post in the following link link: Change default Synchronization & Storage settings

But I don't see the "mbox" and "msf" files that are many GB in size that I should delete (or rename). What files should I delete in Tbird's profile folder to get rid of previously downloaded email bodies?

Thanks for your help, Skyzoomer

Help/Troubleshooting, Profile Folder, Open Folder, close TB. Open the account subfolder of ImapMail, e.g. ImapMail/imap.gmail.com, and look for the mbox files, the large files with no extension, named after folders. Each mbox file is accompanied by a like-named .msf index file. Delete the mbox and msf files if you no longer download full messages, as set in Synchronization & Storage settings. Upon restart, TB will recreate the msf files, but message bodies will be downloaded when messages are opened, and stored in the cache. An mbox file will not be created, unless synchronization is set for a specific time period.

@sfhowes,

Thank you very much for explaining what the mbox files are (large files with no extension). No where did I ever see that explanation in the hours of Googling that I did. And that the mbox files are accompanied by a like-named .msf index file.

Armed with that info, I then understood what the "Sent-1, Inbox, and All Mail" mbox and .msf files were. (Those 3 mbox files were in the 7-9 GB size each.) I tried to be safe so I renamed those 3 pairs of files with a ~ prefix. I figured if Tbird worked normally when I opened it, then I could delete those 3 pairs of files.

Much to my chagrin, after I opened Tbird and then checked where those 3 pairs of files were, I discovered that Tbird deleted the ~prefix files all by itself and created the replacement .msf files.

End result is that my Tbird profile folder went from 29.3 GB to 5.68 GB. And Tbird is working normally so far. I was hoping to get the profile folder size below 1 GB but I'm satisfied with the 5.68 GB size.

For lurkers who might try this procedure, the imap.gmail.com folder had the Sent-1 file pair. One level down, the [gmail].sbd folder had the Inbox and All Mail file pairs.

Thanks for taking the time to help me. I marked your last post as the solution. Very much appreciated as I would never have figured it out without your help. skyzoomer

Provided I use the following setting: ... Tools > Account settings > Synchronization & Storage > Disk Space > Synchronize the most recent _1_ week

I don't understand what you are trying to achieve with this approach. Using this setting you avoid initially downloading your entire email archive from the IMAP server, except for the most recent week. Further down the road Thunderbird will continue to download all new messages you receive. It will not erase downloaded message bodies older than one week, as you already found out.

So all you've achieved is to erase your backup for messages older than one week, unless you do keep your previous full backup indefinitely. Any future backups will continue to grow in size over time as you get new messages for your IMAP account.

Note, keeping messages on an IMAP server is no replacement for proper local backups.

@christ1, Yikes! I don't want to keep adding message bodies and my Tbird profile keep growing in size. Thanks for letting me know!

Is there a way to use Tbird with gmail accounts without having message bodies stored in Tbird's profile folder? If just the header for each message is stored in the profile, that would be OK.

Being a Tbird dummy, if there's a way, please explain with that in mind.

Thanks! skyzoomer

In Tbird I have "Keep messages in all folders for this account on this computer" unchecked for every account. I assume with that unchecked, only the message headers will be stored in my Tbird profile folder.

Hope that's correct, Skyzoomer

That should do it, and to check, look in the profile folder and see that there are only .msf files and no mbox files of the same name. Delete any leftover mbox files if necessary.

@sfhowes said: That should do it, and to check, look in the profile folder and see that there are only .msf files and no mbox files of the same name. Delete any leftover mbox files if necessary.

@skyzoomer said: I will do that. Thanks! Skyzoomer

As said before, you won't have a local backup then. Good luck.

@christ1 said: As said before, you won't have a local backup then. Good luck

@Skyzoomer said: Hi christ1. Please re-read my original post. The whole purpose of reducing the size of the Tbird profile folder was to make smaller and faster backups of it. Regards, Skyzoomer