Bug 336058

I have two instances open of kmail (seperate computers) and spamfiltering enabled with spamassassin. 
Every now and then when a mail arrives it is run through rule 1 (spamassassin -L). This rewrites the header and the mail arrvies as new again and is rerun against spamassasin -L. This loop can go on for a while and produces dozens of duplicate mails

Reproducible: Always

Steps to Reproduce:
1. Enable spam filtering on two computers with the same imap account
2. Wait or test mail incoming

Actual Results:  
The spamfiltering process runs like wild in a loop and produces duplicates

Expected Results:  
Check incoming mail locally once and don't write a new header which makes other mail clients running thinking a new mail arrived. 

Tested on latest kmail, akonadi and spamassassin + bogofilter.

Even when kmail is running only on one computer I see In the filtering log many many rescans of the same file over and over again. Also my smartphone shows me tons of duplicates then (seems like it does not keep up with tons and tons of rewriting header mails)