[Sieve] Multiple email recipients, how?

[Robert]

Hi,

First, I am very new to using Pigeonhole/Sieve with Dovecot and I am 
struggling with a problem which could be easy to solve but is just a 
lack of understanding on my end...

We use a simple system for routing emails to different email users by 
postfixing the addresses with the actual user: xxxJohn at domain; 
yyyJohn at domain etc all will be delivered to user John.
(This way John can invent a new email address on-the-fly and that will 
be delivered to his email box.)
Delivering these emails to the right mailbox is easy:  if address 
:contains "to" "John" ...
All mail not matched will go to the general (catchall) mail box.

The problem occurs when the email is sent to more addresses at the same 
domain.  Eg. if an email is sent to xxxJohn at domain, zzzAlex at domain and 
info at domain
Either, all emails also end up in the catch-all, or the email is 
delivered to the first matching rule only.

I do not understand how to use the different TO addresses in the match 
rules. How can I determine that there are recipients other than xxxJohn 
or zzzAlex?

Any help in pointing me in the right direction is appreciated!

Robert