HELP mail @hostname not mail@individual domain(multi)

[STend]

-fairly newb disclaimer-

mail always out as unixuser@host.domain.tld


[multiple domain box]

like recip to see
from: user1@example1.tld
or
from: user2@example2.tld

i.e. from: should be dependent on domain.tld of that user

Have sanitized postfix main and master ready.

sends and recieves fine, recv as virt fine sort by indiv dom.