Receive email, filtering

[Piet]

Dear List,

before I use email with several devices, I used fetchmail and procmail
to receive and filter email.

I switched from pop3 to (external) imap and have some question how to deal with 
mutt and mailfiltering.

It seems, that fetchmail  receives emails from imap, but only in two
ways which can not be combined:

1. 'Fetchall'  and delete the messages (option fetchall).
	Problem: Messages are not avaible for other devices anymore on
	external imap.
Or 

2. Fetch only the unread messages (option 'keep') and keep the messages.
	Problem: Messages which are aleady red will not be fetched.

Both ways do not fit to my needs.
I'm not 100% sure if I understand how fetchmail is working.

Further I try mbsync, but it seems not to work with procmail.
Getmail seems to work similar to fetchmail.
I don't like to use 'sieve', because not all imap provider offer this. 

Is there the opportunity to fetch and filter email without deleting it in
the external imap account?

Thank you for your tipps!

Kind regards

Piet