Sending email from computers on the CUDN

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.

Hermes users

Most people in the University use Hermes for email. The Hermes message submission service, called smtp.hermes.cam.ac.uk, is intended for Hermes users to send email from a variety of mail programs (clients). All email sent via smtp.hermes.cam.ac.uk must be securely authenticated.

If you are simply a Hermes user needing to configure your computer within the CUDN to use Hermes you do not need this page; see the page on email program settings for Hermes instead.

Using other addresses with Hermes

You do not have to use your @cam or @hermes address when sending email via Hermes. In particular, many departments, colleges, and research groups which do not run their own email servers use the Managed Mail Domain service, which provides special email addresses for use with Hermes. For example, the bursar of St Botolph's college might use the address bursar@botolph.cam.ac.uk, or the maintainer of a project web site may use the address webmaster@silentspeedboat.org. See Managed Mail Domains for more information.

You can also, if you wish, send mail via Hermes using addresses at mail domains which are not managed by the Computing Service, though in this case there is normally the alternative of using the facilities offered by your mail provider.

The secure authentication requirement still applies whatever email address you use. Hermes ensures that authenticated senders are clearly identified in the messages' headers, to avoid confusion.

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 Hermes. 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 rather than via Hermes. The Computing Service cannot provide advice on the specifics - there are too many different systems out there for us to keep track of them all.

If you mainly use Hermes rather than your departmental email system, you can still use your departmental email address with Hermes as described above.

Sending email from home or when travelling

Roaming users should send email via their "home" server if possible. For example, Hermes users can send email via smtp.hermes.cam.ac.uk from anywhere on the Internet if their software is correctly configured for secure authentication, as described in email program settings for Hermes.

In the past, before the secure authentication facility was available, we said that roaming users should use the local ISP's smart host as their SMTP server. This is no longer recommended because it is increasingly the case that anti-spam protocols check that the "from" address on messages corresponds to the originating server.

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

Similarly, 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 who uses Herald for email, you should send via smtp.ox.ac.uk.

However, note that because of the port 25 block (see below), 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.