7. What happens when I send mail?
Each mail message has a mail header associated with it. This provides information such as the address of the sender, when it was sent, and so on. When mail is sent from a system in Oxford the message is passed to the central mailer, which checks that the domain part of the address to which it is being sent is valid (if not, it rejects the message), and then passes the message onto the wider network to the relevant machine. The mailer includes in the header a value for the "Sender's address" - this will be the relevant generic address. People may choose which of their affiliations (department or college) is used to make up the outgoing mail header.