Dear Friends,
I am using rpm based Linux system (Centos) and I have configured
sendmail and dovecot server comes default with it. As per the config i
ve made it is working fine for system users.

To setup the mail server for virtual users I have downloaded dovecot
source from and compiled in a root shell and followed the
virtual user configuration for pain text authentication according to

>From sendmail end I have add the mailer(dovecot) entry to the file, adding the content given the site
and created the required dovecot.m4 file, created the file
and started the sendmail + dovecot.

But I still get the user unknown error when mail client try to send a
mail to smtp sever (sendmail). Client gives error,
The message could not be sent because one of the recipients was
rejected by the server. The rejected e-mail address was
''. Subject 'test', Account: '', Server:
'', Protocol: SMTP, Server Response: '550 5.1.1 < k>... User unknown', Port: 25, Secure(SSL): No,
Server Error: 550, Error Number: 0x800CCC79

But dovecot authentication is happening and mails are receiving when I
send mail from root shell is happening and dovecot.log and info.log
gives authentication ok for user abc.

When I check the maillog it says as,
Oct 3 07:39:43 user1 sendmail[4173]: l9329hgq004173: < k >... User unknown
Oct 3 07:39:43 user1 sendmail[4173]: l9329hgq004173: from=< k >, size=0, class=0, nrcpts=0, proto=SMTP,
daemon=MTA, relay=[]

What went wrong for sendmail? Pls give me necessary steps in at lease
point form do this sendmail config for virtual users?