Hello folks 
I’ve inherited an ancient server running under Suse linux that give me some problems and headache…
as configuration it have :
an FQDN : say 'mycompany DOT com'
all DNS and reverse DNS stuff are configured fine,
it runs some websites like 'blog DOT mycompany DOT com' or 'forum DOT mycompany DOT com' AND is also configured as 'mail DOT mycompany DOT com'. running Postfix :)
it have some users with accounts and homes directories stuff, : say ‘user1, user2, boss, sales, webmaster, wooky’…
some of these users can use an email address of type 'username AT mycompany DOT com' to send and receive emails to and from anywhere. say 'boss, sales, webmaster' can, all the others cannot.
I need to add some new users and ensure that they can use fully the emails like ‘boss’ and the two others, as ‘newuser1 AT mycompany DOT com’ and ‘newuser2 AT mycompany DOT com’.
Now the problem :
I’ve been able to create these new users fine and can login under their username on the server without problems.
now if I try to send or receive emails using the wanted ‘newuser1 AT mycompany DOT com’ address I can’t 
receiving emails for ‘newuser1 AT mycompany DOT com’ is impossible, emails are bounced as ‘user unknown’
‘’‘newuser1 AT mycompany DOT com: host mail DOT mycompany DOT com[some address] said: 550 5.1.1 newuser1 AT mycompany DOT com: Recipient address rejected: User unknown in virtual mailbox table (in reply to RCPT TO command)’‘’
is what I get…
So, as there are working users like ‘boss’ that can send and receive emails as ‘boss AT mycompany DOT com’ fine I’ve crawled the entire server and all sorts of configuration files (tons of) to try to find how this was possible for ‘boss’ and why any new user created can’t.
I found the corresponding mailboxes in ‘/var/mail’ and ‘/var/spool/mail’ BUT strictly no references to ‘boss AT mycompany DOT com’ or others working users email address anywhere in the server configuration files ! no traces of it even in Postfix configs or various databases…
the /etc/postfix/virtual config file is untouched since postfix installation, and I found the ‘boss AT mycompany DOT com’ address ONLY in the ‘/etc/postfix/whitelist’ config file, with a ‘OK’
after it…
So, I’ve tried to add ‘newuser AT mycompany DOT com OK’ to that ‘/etc/postfix/whitelist’ config file and ran ‘postmap /etc/postfix/whitelist’ to reconstruct the db, then restarted postfix.
I then ran tests to see if the problem was gone but NO still won’t work…
I’m puzzled.
Now the question(s) :
How the heck 'boss AT mycompany DOT com' for old existing 'boss' account can be used at all for email stuff when it is impossible for any new added users to do the same ?
How 'boss' user have been granted the use of his 'boss AT mycompany DOT com' email address ?
I really want to understand that and get successful working emails for ‘newuser’ too.
I’ve read a tad load of stuff on the web but haven’t found the answer to this problem yet as nothing suggested worked at all to correct this.
so I try there in case some wizard can help me to understand and correct this problem
thanks by advance,