University of Waterloo Anti-Spam Features

The University of Waterloo uses a number of features available with sendmail to reduce the amount of unsolicited junk email (spam) delivered to people's electronic mailboxes:

the sender's address must be fully qualified (ie. sender e-mail address must be of the form userid@domainname)
the domain name in the sender's envelope address must resolve (ie. reject e-mail with a source e-mail address of userid@domainname if "domainname" does not exist)
only accept for relaying to other systems e-mail which comes from trusted clients (pre-authenticated clients on most mail servers)
reject e-mail from non-uwaterloo.ca hosts which are blacklisted as known spam sources or open relays, according to one or more widely used databases such as the

What happens when someone sends e-mail to a UW recipient from a blacklisted site ?

When someone sends e-mail to a UW recipient from a blacklisted site, they receive an error message which includes a reference to either the web site associated with the blacklist or a web page at the University of Waterloo (such as http://mailservices.uwaterloo.ca/RejectedMail.html or http://www.eng.uwaterloo.ca/~eng_comp/rejected_mail.shtml) which describes why the email was rejected and what the sender can do about it.

What if I want to receive all e-mail addressed to me, regardless of where it comes from?

Anyone with a UWdir userid (click here to verify your UWdir userid and/or password) can opt out of the blacklist checks by filling out this form. You can opt back into the checking (and check whether you're exempting your incoming mail from blacklists or not) with the same form. Your system administrator must be running sendmail version 8.10 or later (the full headers of email you receive will contain text similar to

Received: from AAA.BBB.CCC (AAA.BBB.CCC [www.xxx.yyy.zzz])
        by email-server.uwaterloo.ca (8.x.y/8.x.y) with ESMTP id

, where the 8.x.y/8.x.y tells you the version of sendmail on email-server.uwaterloo.ca) configured to use the campus-wide blacklist opt-out list (or users must send mail to your userid@uwaterloo.ca email address) for this feature to take effect. If you wish to have a mail address which is not in UWdir opt out of the filtering and receive all email addressed to it, please talk to your system administrator who can make arrangements to get the address on the opt-out list.

What if I've got a uwaterloo.ca userid, but I can't send mail from home

If you get the error message "Relaying denied" when sending mail from your computer at home, you're probably trying to relay your outgoing mail through an on-campus machine, rather than through your Internet Service Provider's outgoing mail (SMTP) server. Many on-campus machines will not allow any relaying of mail from off-campus sites.

Last modified 24 February 2004, Dawn Keenan