Is it possible to get a documentation for that ?
Or a description how to implement that ?

"Oliver" == Oliver Glas <oliver.glas@inss.ch> writes:

I am looking for a way to remove attachments, based on a condition.
Like attachments starting with "TimeReport" shall be removed, and
then the mail should be delivered, with all other attachments.

This is not a solution that dovecat can work with.  You need to use a
milter in your mailserver (like postfix) which can strip out mime
attachements or do other modifications to an email before it's
delivered to the mailbox.  

I did so far not find a solution to remove attachments.  Do I need a
plugin / extension  ? If so, how to implement and use that ?

milters are what you want.  MIMEdefang is one.  

John