[quote user="Jonas"]One reference had "Name_Unavailable" in the line.

Many other lines also contain that string. Therefore I have the question if I can remove those lines too.[/quote]

Yes, these are "cached" entries of whatever Pegasus Mail registered before, deleting them doesn't cause any serious issues.

I have a problem with an empty tray. It can't get deleted.  When deleting it complains about containing a folder which needs to get removed first. But it doesn't contain a folder.

The tray once has a folder which was deleted including the tray. A new mail triggered a filter which referred to the folder and recreated the tray, but not the folder.

How can I remove the tray?

[quote user="Jonas"]How can I remove the tray?[/quote]

Did you delete the filter rule so you don't encounter this issue again? Then open Help => About Pegasus Mail => Info and pick the home mailbox location, close Pegasus Mail, go to this directory via Windows explorer, open the file HIERARCH.PM with a plain text editor (Notepad, e.g., no Office application!) and search for the name of the tray (and maybe the invisible folder as well): After creating a backup of this file (just in case something goes wrong) delete the respective lines and restart Pegasus Mail.

Edited the file and removed two references. And it works, thanks!

One reference had "Name_Unavailable" in the line.

Many other lines also contain that string. Therefore I have the question if I can remove those lines too.