I installed Ioncube using steps mentioned here
The SMTP is being troublesome since then.
* I am able to receive emails in outlook
* I am able to send receive emails in roudcude
* I am NOT able to send mails using Outlook.
The message I see in /var/log/maillog is
May 1 11:47:49 server dovecot: auth-worker(15829): shadow(firstname.lastname@example.org,ip.ip.ip.ip): unknown user
May 1 11:47:49 server dovecot: auth: passwd(email@example.com,ip.ip.ip.ip): unknown user
Error in Email Clients:
[5/1/2012 11:58:43 AM] Mail and chat
Sending email failed. Maybe the SMTP server is not set up properly? Email queued.
I am not able to find solution of this error on forum.