IMAP accounts.
After an email has been deleted it moves to trash folder. On next sync it returns as a greyed out email which cannot be accessed/dealt with in any way.

The waste-bin can be emptied as normal.

Using another email client (evolution), the deleted emails do not show up as greyed out (they don't show up at all in their original folder), but are in the Trash folder. Deleting them here removes the greyed out emails in kMail2.

John

Reproducible: Always

Steps to Reproduce:
1. Delete an email
2. Wait for sync
3. Grey email appears
Actual Results:  
deleted email appears as greyed out in its original folder and cannot be accessed.
Checking the emails on the mail server (courier) the emails are present in the original folder.

Expected Results:  
Email should disappear

Evolution shows the greyed out emails in the Trash folder. Deleting them here removes them from the server, and from kmail2.