Error sending mail from off-network... (details inside)

[Subhro]

Are you authenticating yourself before attempting to send out mail to
the ISP SMTP. To prevent spammers, almost all ISPs allow the use of
their SMTPs only after you prove them that you are really a legitimate
customer. Also many ISPs wont allow you to use their mailservers
unless the IP which you are using (rather which had been assigned to
you) belongs to their own pool.

Regards
S.

-- 
Subhro Sankha Kar
School of Information Technology
Block AQ-13/1 Sector V
ZIP 700091
India