Postfix offers the possibility to configure extension addresses, over recipient_delimiters: Postfix Configuration Parameters search for the recipient_delimiter option.
I tried configuring this in the local Postfix from BlueMind, but then the core wouldn’t accept any such E-Mails. Our support partners are claiming we can not do this change, even if we were told we can do any change to the underlying mechanisms, because you know… open source, and not just another not configurable monolithic app like some specific well known mail provider.
Is this really so?