Emails not going for subscribed threads

[Steve Machol]

This is a server configuration problem. Read this:

http://www.vbulletin.com/forum/showp...6&postcount=20

[amanpartaps]

My members are not getting emails for subscribed threads...

I had run the diagnostic... it said

SMTP: localhost

sendmail_from: None

sendmail_path: /usr/sbin/sendmail -t -i

Why is showing None in sendmail_from ? I have already toggled -f option as well... but with no success.

I had sent the mails through diagnostic but email is returned saying

unrouteable mail domain

Please do something...