Is postfix able to rewrite the recipients, based on the sender address?
There are multiple users receiving Mail by this configuration in /etc/postfix/virtual:
mail@example.com user1, user2, user3, user4
But whenever userX sends a mail@example.com, userX receives its own mail.
Is Mailman the right Tool for this job?
Postfix itself can't exclude sender from the alias. The reason is the lookup just has one parameter, either sender or recipient.
Mailman is a mailing lists manager. Yes it has functionality to forward email to members list as your example above. As a bonus, mailman has advanced feature of mailing list like list-admin, members management, bounce management and archiving.
Your request to exclude sender to get his own message, mailman has it too. Take a look to this thread and this one. Basically, you should set option Do not send a copy of a member's own post in mailman list.
One caveats: if you use mailman in virtual domain environment, it has limitation. Suppose you have domain example.com and example.net, then you can't have both lists@example.com and lists@example.net because listname must be globally unique within a single Mailman instance, i.e., two lists may not have the same name even if they are in different domains.
