The mail user returns saying unknown user.

I am trying to add a mail user to iplanet messaging server 5.1, I am able to configure that user from my mail client (outlook) but when i send mail to that user, it returns saying unknown user. I can see that user in LDAP data base.
[246 byte] By [708728] at [2007-11-25 7:09:02]
# 1
Try the ./imsimta dirsync -F command.Try to manually login to the user through pop or imap and see if you can get his mailbox listed.
708730 at 2007-6-29 17:40:19 > top of Java-index,E-Mail, Calendar, & Collaboration,Sun Java System Messaging Server...