With a little research i found out that every big email provider has an option to see from which ip address the message came from. I think it is the right of the receiver to know who sent the message as usernames can be anything and username is not a good idea to know the sender.

When i emailed to myself on sajha.com, then in my yahoo inbox which is my contact mail, i received a mail saying that i got a mail. There i found that the sender ip address was that of sajha.com as the one who emailed me on yahoo was sajha not myself (i emailed myself on sajha inbox).

So, SAN(i think he is the administrator) i think you should also provide the facility to see the ip address of the sender in sajha inbox.