Years ago I used a control panel at Strato in Germany (Vista24, proprietary and now dead). They had a special feature in mail forwarding.
With i-MSCP you can have
- an e-mail box
- an e-mail forwarder to one or more addresses, even cascade them 
- a catchall address
In the mentioned program there was additionally
- a forwarder for a multiple of addresses
Example:
I have subscribed to many newsletters, each with its own mailadress, say
letter01@mydomain.tld pour Figaro
letter02@mydomain.tld pour Le Monde
letter03@mydomain.tld pour Financial Times
itgeek01@mydomain.tld pour Framasoft
itgeek02@mydomain.tld pour Opensaar e.V.
itgeek03@mydomain.tld pour i-MSCP News
Formerly I had forwarders like
letter* -> letter@mydomain.tld (being an imap-account, called separately from other mails)
itgeek* -> geek@mydomain.tld
I tested with i-MSCP and wildcards were accepted, but not working as such but literally 
So my question is: could this be implemented without much work? Just by giving postoffice programs a regular expression?
If this would not be possible I'm happy I read of another solution in this forum. There s. o. suggested to create appropriate subdomains, e. g. in this case letter.mydomain.tld and itgeek.mydomain.tld.
Beyond comfort there is another reason for my question/suggestion. Today it happens more often, that mail addresses get lost because they get on spam lists. While still receiving valid mails amidst spam you can put them out of your everyday box when naming of the addresses is somehow structured (name-YY-MM). In praxis it happens like this: on a webpage I discover an interesting new newsletter. Without need for creating a new address for that I can order this letter by using the next number (letter04@mydomain.tld in the example above). This address is already covered by my "catchmultiple"-forwarder. The frontend needn't be changed with such a solution.
What do you think?