I have been shying away from upgrading my laptop from the 16.04 LTS for 2 1/2 years for fear of losing data. This despite doing regular backups. Finally bit the bullet as 16.04 goes out of support this month. The 'do-release-upgrade' to 18.04, then to 20.04 went smoothly, but it took ages for the machine to reboot each time. Question: I use kmail as my email client, and now the tab on the desktop panel has a number on it. Sometimes this relates to the number of unread mails in the inbox, but at others it is an apparently randomly incrementing number. Does anyone know what this number really represents, and how do I configure it?