I use PRTG IMAP Sensor for a few Backupmails. Now I have the problem that it does not find any email in the mailbox which has () or  in the subject. I tried with string search and regular expression. Could that be a problem? If I configure the Sensor to NOT search for subject, then it is becoming green.
It happens when looking for emails younger than 48hours. But there is one in the mailbox, but as I said with special characters in the subject. If I remove search for subject, it works.