in my windows application, i am accessing the smtp of a server, and sending mail using the system.net.mail, i could able to send mail to email address which does not have a .(dot) in the address section. (ie) - i can send mail to firstname.lastname@example.org, but when i try to send mail to email@example.com.. smtp mail sending is failed and and error is thrown.
the error message is:
"Mailbox unavailable. The server response was: 5.7.1 Unable to relay for firstname.lastname@example.org"