I cannot send a message from my METU account to an external e-mail address which has been directed to an address in METU. Why?
E-mail messages sent from a usermetu.edu.tr structured e-mail address to an e-mail address with the same structure; in other words, e-mail messages with "usermetu.edu.tr" for both the "To:" and "From:" fields (the sender and the recipient are the same) are blocked unless they are sent via "mail.metu.edu.tr" server.
This procedure is applied in order to block the unwanted messages from out of campus sources, like fake and/or spam messages, to be distributed.
For this reason, when you direct the e-mail account provided by an email service provider from outside of METU to the e-mail address with the METU central user code, e-mail messages sent from an account with a METU field name will be classified as fake/spam e-mail and blocked by the central servers since it will be conveyed through a server which is out of campus.
Important: Directing from departmental e-mail accounts (e.g. xxxxx.metu.edu.tr) is not within the scope and therefore is not blocked.