Since PM 4.7 and with preview-mode I sometimes have a mailentry in the folder, which is greyed and has a dashed line. Those entries are always entries of mails, I have moved before to another folder. Meanwhile I have selected another folder and the entry appears, if I select again that folder formerly holding the mail. Sometimes the dashed entry disappears, if I choose another folder and then reselect that folder - but not always:
Just clicking the mailfolder for updating it never lets disappear the dashed mail. Up to now this only happended with IMAP-folders - but my use of local folders is very low.
bye Olaf