The file accumulates all the emails that ever go through the folder and the data file increases. This is why compacting is important as it periodically removes all the 'space' that is tied up but not used. Set the limit to a small figure like 100MB to have it compact more often the default.

thank you but I have never "compacted" anyhing..how does one do that? Will I loose access to any emails? None of my email accounts are pop...and I have hot mail, gmail and Yahoo

I have never "compacted" anything. How does one do that. I have several accounts like gmail, yahoo, hotmail etc..all are IMAP. Will I still have access to all these compacted emails?

I got gutsy and right clicked on several of the Local folders and said to compact..seems like nothing happened..no message of done or not and I do not see a difference in my profile size..am I doing something wrong?

I also poked around and found in TB Tools>General>Disc space> a message that said mu cache is over 1.0GB and an option to Clear Now? The next line is set to compact over 500 MB and ask before compacting. Should I clear?

I set my compaction size to 100MB and to ask before doing it (so I can make sure I'm not accessing emails and folders while it's being done). The cache is something different. I think it means all the web items that are embedded into the emails - so if you delete the cache, some emails will need to download the content again. So there's no need to do that.

Again, thank you--Where do you set the compaction size in the settings? I will leave that cache alone. Upon reading I guess I am concerned about a minor thing as my profile is 339 MB, 2074 files and 64 folders and that may be small but I never saw a decrease after cleaning out things.

Compaction is a process, not a setting. In compacting, Thunderbird attempts to remove messages that have been deleted. Sometimes, the compacting fails, leaving interim files in the profile with nstmp suffixes. If that happens, those folders may be deleted.

so I tried a right click on Local folders and a pop up said I did not have permission or enough room..and when I tried again..no message even one saying compacting worked..

I do not see any stmp files when I sort by type

I have a lot of 0 files when I sort by size- screenshot attached

so I went thru all the folders individually and compacted them..Yes the file size went down but the number of files increased? Before and after screenshots..

Again, thank you--Where do you set the compaction size in the settings? I will leave that cache alone. Upon reading I guess I am concerned about a minor thing as my profile is 339 MB, 2074 files and 64 folders and that may be small but I never saw a decrease after cleaning out things.

In the Settings, under 'General'. Scroll down on the right to 'Disk Space' and you can set the threshold for compaction there. I've actually set mine to 50MB but the default is much higher.

You won't see a decrease in size after deleting emails. The data files are cumulative and are only reduced with compaction.

Thank you..I guess I should just leave as is for now as it isnt broken..thank you for your help..Happy Holidays