How to Compact Folders in Mozilla Thunderbird
Select File > Compact Folders. If your folders are large and you deleted lots of messages since the last compacting, this process may take some time.
How to Compact Folders Automatically
You can set up Mozilla Thunderbird to free disk space automatically—with or without prompting. Here’s how:
Folder Compacting Options and Settings
To compact a folder when prompted, select Compact Now under Do you wish to compact all local and offline folders to save disk space. To make Mozilla Thunderbird compact without prompting in the future, make sure Always ask me before compacting folders automatically is not checked. To choose whether you are prompted when Mozilla Thunderbird is about to compact folders automatically:
False does not prompt you when automatically compacting folders.True asks you before compacting folders automatically.
