This is one of two pages discussing different ways to configure a computer to send email from the CUDN without encountering problems. They are concerned only with outgoing mail (SMTP) settings and not with incoming mail (IMAP or POP). The other page is concerned with messages that are not sent manually, and will be of interest mainly to Institutions and technical contacts.
Note that the central email systems filter outgoing email for viruses and other potential security problems. This includes certain file types that may include executable code. You can avoid the file type restrictions by zipping files before sending them as email attachments; this also reduces the size of the message. The scanner is documented at the central email scanner.
Office 365 Users
Most people in the University use Microsoft Office 365 for email. Microsoft have a page documenting on the settings for sending email via Office 365 at https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/how-to-set-up-a-multifunction-device-or-application-to-send-email-using-microsoft-365-or-office-365. All email sent via Office 365 must be sent authenticated with 2-Factor authentication.
Users of college or department email systems
Other email systems in the University (belonging to institutions which do run their own mail servers) provide a message submission (SMTP) service similar to the facilities provided by Office 365. If you are a user of such a department or college email system then you should normally configure your software to send email via that system's message submission service. Information Services cannot provide advice on the specifics.
Sending email from home or when travelling
Roaming users should send email via their "home" server if possible. For example, Office 365 users can send email via smtp.office365.com from anywhere on the Internet.
Users of college or department email systems should consult their computer officers for advice about message submission when away from the University.
Users of non-University mail systems
Users of external email services should configure their software to use that service's message submission servers. For example, if you are a visitor from Oxford, you should send via smtp.ox.ac.uk.
However, note that because of the port 25 block, you must configure your software to use an alternative port, usually one of 587 or 465 depending on what your software and email service supports. If your email service doesn't provide a message submission server on an alternative port, you can use the smart host ppsw.cam.ac.uk port 25 to send email. In this case you must turn off any security or authentication options for SMTP, but leave them on for IMAP or POP.
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