See https://support.mozilla.org/en-US/kb/compacting-folders

Thank you. An interesting article but rather irrelevant to the question.

Thank you. An interesting article but rather irrelevant to the question.

Actually exactly on point. When you "move" an email it is deleted from the current folder and a newly created copy is appended to the folder you moved it to. SO you probably have a gigabyte or more of old junk clogging up your inbox for no reason other than you simply do not understand how the process works.

If your account is IMAP, the copies in the inbox never get removed their either, so you can change the server settings for the account to just mark it as deleted to see the list of "moved" mail that was not moved as all and is still in the folder taking up space.

My guess is you are using IMAP and your server Quota is getting full so the server is begging you to purge some junk before they just disable your account as FULL. I am guessing this as Thunderbird does not use the term Purge, but Imap servers do. So messages refering to Purge usually original at the server and Thunderbird just displays them

Thank you for assuming I'm stupid. I'm using POP and the server is on a rack behind me. I'm just, suddenly with this new release 78.3.2, getting a message that I have to answer Cancel to every time and I'm getting very tired of it and I want to get rid of it. It goes against the grain to back date a version as that's never safe long term.

Why don't you disable the Compact all folders when it will save over setting in Options and see if you still get that prompt?

re :An interesting article but rather irrelevant to the question. I can only assume you gave it only a cursory glance as the information explained where you had a setting to switch auto compacting off or on and set a threshold. I will agree that the information is now a little dated and needs some updating. But the info is still the same.

The pop up message is because you have a setting that is asking you compact when it will save you x amount of space. You are seeing it because you have reached the threshold that is set.

• Menu app icon > Options
• select 'General'
• scroll down to the bottom to locate 'Disc Space' section.
• uncheck the checkbox, (so not selected) 'compact all folders when it will save over x mb in total'

Just so you, or indeed anyone else who reads this, really understands what is occurring and that you realise you could be increasing the risk of ending up with a corrupted file. Emails are stored in mbox files. An mbox file is a simple text document. So lets discuss the Inbox. As you download emails they are written to that one single text document, one after the other, so the oldest will be at the top. If you imagine it like one email is a paragraph, then you can understand there is a lot of paragraphs in that one single document. When you delete or move an email, it gets marked as deleted, so to use the paragraph example, that paragraph gets the red pen treatment as a strikethough, but the text remains. After a while, the one single document will contain more deleted or moved emails than ones you keep in the Inbox. So using the paragraph example, you can now easily understand that the document looks a mess and is now hundreds of pages in length, yet only has a few emails/paragraphs you want to keep in that one single text document. Needless to say, it is also a lot bigger than it needs to be because of all the stuff you have either moved or do not want anyway. Compacting means getting rid of all the stuff you have moved or deleted, so the file becomes smaller, so uses less space, less memory to open, speeds up handling of file and is less likely to have corruption occuring.

If you want to continue as you are and never compact then you need to understand you could end up with a file that might not be able to be opened very easily using a text editor program should you ever need to recover emails. You are increasing the risk of losing everything contained in that file.

I presume you are already creating backups, but if not then I strongly recommend you create regular backups of your profile folders because as time goes by those risks increase.

Alternatively, you can manually compact individual folders. right click on folder in Folder Pane and select 'compact'

The folders that usually require this the most are 'Inbox', 'Drafts' and 'Junk'.

Thank you for the fuller explanation. I've turned auto compact off and restarted Thunderbird and the message has gone away. Weirdly I have had auto compact on and seen 'compacting' messages very often but never been asked about it before. 'Different' is usually bad news in my book. I read 'Deleted Messages' as my deleted messages folders and the wording worried me. Perhaps Options | General | Network & Disk Space | Compact all folders when... works slightly differently now.

Either way thanks for sorting my head out guys. I will manually compact things then turn the option back on.

Thanks to Toad-Hall above for a solution to the Thunderbird error message "The messages you have deleted can be purged from disk" that began appearing on my wife's PC recently. Larry

Alternatively, you can manually compact individual folders. right click on folder in Folder Pane and select 'compact' The folders that usually require this the most are 'Inbox', 'Drafts' and 'Junk'.

Thanks for explanation. I was under the impression that the Clean up ("Expunge") Inbox on Exit and Empty Trash on Exit took care of that, but I guess not? I don't recall seeing this popup message in TB68

re : I was under the impression that the Clean up ("Expunge") Inbox on Exit and Empty Trash on Exit took care of that,

For IMAP accounts, the above does auto compact the Inbox and empty the Trash on exit. It is not auto compacting other folders.

Note: not everyone exits Thunderbird, some just minimise and laptop goes into sleep mode.

Compact cleans up marked as deleted mail. Please note this is not just emails you selected to delete - send to Trash. It also includes emails that have been 'moved' to another folder and so need to be cleaned from the folder they no longer are stored in.

Set up an auto compact prompt - useful for POP accounts and also IMAP as it covers more than the Inbox. A useful prompt

• Menu app icon > Options
• select 'General'
• scroll down to the bottom to locate 'Disc Space' section.
• Select checkbox : 'compact all folders when it will save over x mb in total' suggest you set xmb to be on the low side eg: 20mb as frequent compacting is less risky. But it is up to you.

You do not have to select the above if you prefer to manually compact folders on a regular basis.

The popup message is misleading. It should say something like "Your Inbox can be compacted, which will free up XX MBytes of disk space. Compact now?"

Could the Thunderbird developers improve the message? Or must that be done in the IMAP server (gmail)?

"The messages you have deleted" obviously means messages I select and press the Delete key. Which moves them into my Trash folder, I understand.

I read 'Deleted Messages' as my deleted messages folders and the wording worried me.

Totally agree. It is very misleading.

I have created a bugzilla request for enhancement which you might want to contribute a comment explaining concerns and results, especially if any of you discover it is also 'Empty the Trash' folder. https://bugzilla.mozilla.org/show_bug.cgi?id=1678856

bonjour, (en français !) je suppose avoir le même problème avec cette fenêtre qui apparaît : "les messages que vous avez supprimés ....". Ce n'est pas très précis : est-ce les messages de la corbeille qui vont être supprimés ? cordialement

I went to the web version of my email and deleted all the files in Trash. That dropped my usage from ~150MB to ~24MB. (My maximum allowed is 250MB.) I closed and reopened Thunderbird and the trash folder is now empty but I still have the message to "purge." I never found a folder as described in other Thunderbird help articles so I used TreeSize to find the large folders in my profile and then followed that in File Explorer. I took a screen shot of my profiles folder where there is a single file of 637MB. I then clicked to allow the Purge action in Thunderbird and closed & reopened TB. The message was not there any longer but the size of the file in my profile has not changed.

I went to the web version of my email and deleted all the files in Trash. That dropped my usage from ~150MB to ~24MB. (My maximum allowed is 250MB.) I closed and reopened Thunderbird and the trash folder is now empty but I still have the message to "purge." I never found a folder as described in other Thunderbird help articles so I used TreeSize to find the large folders in my profile and then followed that in File Explorer. I took a screen shot of my profiles folder where there is a single file of 637MB. I then clicked to allow the Purge action in Thunderbird and closed & reopened TB. The message was not there any longer but the size of the file in my profile has not changed.

The folder you are pointing to contains a popstate.dat file. So that account is clearly, and can only be, a POP mail account. The folder you are looking at in Thunderbird you say is IMAP. So there is no connection between the two things at all.

Can you explain a little more? Some time back I followed instructions from TB to get my email so it would sync between TB and the webmail server. I can now move or delete messages in either place and it is mirrored in the other. The server settings in TB say it is an IMAP server. 1 - Do I now have a separate profile other than what is shown in the image I attached? 2 - Where are those messages TB kept encouraging me to delete/compact? 3 - Can that 637MB file and/or any other files in that folder be deleted?

The easiest and accurate way of getting to the profile folder that is in use is to open it through Thunderbird. Go to the Help menu > Troubleshooting Information > Profile row > Open Folder. This will open the correct profile folder in Files Explorer. If it's the same folder that is shown in your screenshot, then you're looking at the message data of a POP account that you were using and probably removed from Thunderbird before you changed to using IMAP.

The Mail subfolder is used by POP accounts while IMAP accounts use the ImapMail subfolder.

You can delete the <pop server name> folder, that is, mail.fishburn.org from the Mail subfolder if you're absolutely sure that it is not being used by a POP account in Thunderbird or if the IMAP account is the only account that you're using in Thunderbird.

Your IMAP account will be in the IMAPmail folder, not the mail folder. The mail.fishburn.com folder will be your pop mail account as at the day your removed it from Thunderbird. Removing an account does not remove the mail data.

You could probably remove the entire folder as it is unused. but I do not know is you actually also still have a pop account configured or not.

Thanks to both of you. I found the IMAP and POP profiles under different users* and deleted the the entire POP profile.

• I created a user with my name but a second was somehow created during the upgrade to Win10. The IMAP profile is in the user folder that Windows automatically created. As you can tell I'm not an expert.