How can I see which mails and folders in Thunderbird take up the most space?

Everyone who uses email will sometimes get the message that your mailbox is too full and that action needs to be taken. Of course, you can just drag and drop everything into a "offline folder" which you then save on your computer. Alternatively, you can be a little more selective and look for the mails and folders that take up the most space and work on those.

How much space does a folder of emails take up?

To get a quick and easy answer to this, take the following steps:

Turn on folder column display via "View > Design > Folder panel columns".

You can now make some additional columns visible by clicking on the very small icon that appears at the top of your folder list :

The names speak for themselves. If you have selected "Size" then sometimes you have to click on the folder to immediately see how much space it takes up.

If you have applied these settings you will see the number of emails in the folder and the amount of space they take up.