SMTP (Port 25) Blocking
What is SMTP?
What is SMTP (Port 25) blocking?
Why does OIT block port 25?
How do I get my system on the exception list?
What is SMTP?
SMTP is short for Simple Mail Transfer Protocol and is the protocol for sending email messages between servers or from a mail client to a mail server. The SMTP protocol is used only for sending email. IMAP and POP protocols are used for retrieving email and are not related to SMTP.
What is SMTP (Port 25) blocking?
A mail server is like an electronic post office that gets all the mail for a particular organization. Blocking SMTP (Port 25) will prevent email from Notre Dame computers from going to any other mail servers on the Internet UNLESS it first goes through the central Notre Dame mail servers or a departmental/personal mail server that has been added to the exception list (see below).
Most users on-campus will not be affected by this block. If your desktop email client or email servers are already configured to use the central Notre Dame email service for sending email, port 25 blocking will have no effect on your ability to send email. Also, the block will have no effect on users of web-based email clients, e.g., Hotmail, YahooMail, etc.
Why does OIT block port 25?
Blocking Port 25 helps to reduce unwanted email (e.g., viruses, spam, etc.) from being sent from Notre Dame computers. The central Notre Dame mail system already provides protection for viruses and catches possible spam attacks, however many viruses, spam-bots, and other security threats mail themselves to other mail servers on the Internet without going through the central Notre Dame email servers. If computers on the Notre Dame network send unwanted email, the entire Notre Dame network could show up on email blacklists. Blocking port 25 helps to control these security threats because it does not allow mail to be sent to other mail servers on the Internet UNLESS it first goes through the central Notre Dame mail servers or a departmental/personal mail server that has been added to the exception list (see below).
How do I get my system on the exception list?
As of July 1, 2006, the OIT no longer accept requests to add systems to the exception list. New departmental mail servers should be configured to use smtp.nd.edu as a smart host, so that all outbound mail is routed through the SMTP servers in the central mail cluster.