while the dialog has a cancel, the right and smart thing to do is click ok. The cancel button is really there so you don't get interrupted by a housekeeping task that will slow the program down if you are pressed for time.

The reality is you must compact at some time. Data loss is the result of permanent failure to do so. Even if it is only from your anti virus finding it now has definitions for the virus containing mail you deleted 6 months ago that is still in the store but hidden because you always press cancel.

Moves and deletions actually do not remove the data from the folder, they just flag it as hidden and make additional copies in other folders. Only compacting does that. In your case you have about 1.2gb of mail that could potentially have a virus or embarrassing information you thought you has deleted that is one click basically from being back in it's original folder.

Matt -

Thanks for the reply.

I'm a little confused. "The messages you have deleted can be purged from disk" strongly suggests that the messages will be permanently erased. If they're not on the disk, then where are they? And if purging them from the disk does not permanently delete them, then how does this action free up lots of disk space? Maybe I don't know the precise definition of "disk" in this context.

Also, the messages I have deleted go into my IMAP trash folder, which has only 155 messages totaling 29MB. So how could purging these deleted messages possibly free up 1.2 GB of disk space? I have 32 folders archived in my "Local Folders" section (I save old emails, organized by year). But when I delete messages, they don't go into any of these archived local folders. And I certainly don't want these archived folders deleted.

> The messages you have deleted can be purged from disk" strongly suggests that the messages will be permanently erased. If they're not on the disk, then where are they? And if purging them from the disk does not permanently delete them, then how does this action free up lots of disk space? Maybe I don't know the precise definition of "disk" in this context.

As the dialog implies, they ARE on disk. The compact process removes messages from folders that you previously deleted to trash or moved to a different folder, because they still take up space in their "old" folder location.

The process does not remove messages that are still visible to you in trash or any other folder. It's just an internal cleanup process. See https://support.mozilla.org/en-US/kb/compacting-folders (which may or may not help)

Wayne -

Thanks for the explanation. And thanks for the link.

When I delete messages from the Inbox, they are visible in the Trash folder. Hence, "The messages you have deleted can be purged from disk" strongly implies that these visible messages will be purged. No distinction is made between visible and invisible messages. (Until now, I had no idea invisible messages existed.)

Maybe the dialog should instead say something like this: "You have 1.2GB of deleted messages which are no longer visible in your trash folder, but are still taking up space on your disk. Click "Okay" to enable Thunderbird to automatically remove these invisible messages from your disk. Messages presently visible in your Trash folder will not be affected."