e-mail spoofing

e-mail spoofing is a technique used to sent the spam mails. In e-mail spoofing the sender address and the other parts of the e-mail header are modified in such a way that the recipient feels that the e-mail was from a different source. If the attacker requires response from the recipient, he adds his e-mail address to the reply to field. This is helpful in finding the attacker. But in some cases the attacker mounts false address in the place of the reply to field. In such cases the the reply of the recipient may badly affect the innocent third person.
There are softwares that generate random e-mail addresses for the attacker to use. If the recipient finds the origin of the email, it is rare that the e-mail is active. Some of the worms uses mass mailing. Here the worm infects a user. When the user opens the e-mail, it triggers the worm and the worm will start reading the address book of the user and then sends e-mail to the other users whose address is in the address book of the first user. If the gateway blocks this infected mail, a message showing that a virus has been blocked.