Imap: Error: Authenticated user not found in db - where users were deleted from Nethserver GUI

[lucag (Luca Gasparini)]

Hi Charles, rebooting will not change that
Find here both the explanation and the solution:

"Zombie User" after deleting one user

Hi @capote, I can confirm that webtop has its own internal cronjob that every 2 minutes looks for any scheduled emails to be sent on all the IMAP accounts it has on its database. If you delete a user on the server without first removing the profile on the webtop, what you reported happens: You have two options to solve: recreate the user on the server, access the webtop admin panel and remove the profile (for example) [Immagine] only subsequently delete the user also from the server …

My 2 cents