This is a technical section describing some of CUIT's mail services, mainly to provide information for school and departmental IT groups.
SMTP is the Simple Mail Transfer Protocol, the standard under which mail is transported on the Internet. Many applications that generate outgoing mail hand it off to an SMTP server that will handle the sometimes complex task of resolving addresses and transporting messages to the destination.
The send.columbia.edu SMTP cluster handles outbound mail from CUIT-managed systems. Individual users should use Lionmail or Microsoft 365 as described above.
Mail automatically generated by other kinds of devices or software is usually not handled on send.columbia.edu. You should never store a username and password in software as a way to use send.columbia.edu. Please see the next section about mx.columbia.edu, and if you don't see how to accomplish what you need to do, please contact CUIT.
CUIT provides the mx.columbia.edu system as an SMTP server for a wide array of devices and software that need an SMTP server to send mail. Mail is accepted by mx.columbia.edu without SMTP authentication. The recipient address must end "@columbia.edu" or "@" another domain hosted by CUIT. No special permission is needed to use mx.columbia.edu. Any host can connect to it. If you need to relay mail to outside addresses, please contact CUIT to make arrangements.
On the Morningside campus, you are not required to route outgoing mail through an SMTP server run by CUIT. If your computer has mail transport software, it is allowed to send mail directly to the destination. The SMTP servers are provided for software and devices that need the assistance of a separate SMTP server. If your application runs on a Linux host run by CUIT, use the host's own SMTP server . Configure the application to connect to localhost (literally the word "localhost") at port 587.