Bugzilla:Using Sendmail for SMTP Authenticaiton

hi,
I configured Bugzilla and wanted to use gmail smtp server for mail delivery, but as Bugzilla does not support SMTP authentication, I used Sendmail for this purpose. but now when I try to commit a new bug, I recieve the following error:

There was an error sending mail from 'sender' to 'reciever':error when closing pipe to /usr/lib/sendmail.exe

(I have used 'sender' and 'reciever' instead of email addresses as the forum rules dont allow use of email addresses for new user)

plz guide me what ever the settings for default domain, and smpt port etc etc. or any thing else ? I have these settings
Smtp port = 25 and
default domain = uffaq.com

and when I use the following settings
Smtp port = 465
default domain = gmail.com

nothing happens and blank internet explorer page appears after some while.

plz guide me in this issue.

its done thanx God !