All students at the University of Waterloo have an @uwaterloo.ca address. All students taking CS courses are expected to check this email account regularly (every 1-2 days, at least). If course staff need to contact you, this is where they send mail. If CS advisors need to contact you, this is where they send mail. Instructions about how to set where this mail gets sent are available on the Quest website.
CSCF has a page explaining more about e-mail, including a link to the centralized UW mailservices e-mail account. IST also maintains an an e-mail information page which describes how to use a number of applications to set up secure e-mail.
If you are planning to use an off-campus address as your destination address, please consider this carefully. Some popular external e-mail providers have flagged all e-mail from uwaterloo.ca as spam in the past, preventing the students using that provider from receiving important e-mails. Also, if you send us e-mail from off-campus, it is more likely to be automatically flagged as spam.
Also, forwarded emails will have your UW email address in the "To:" field, so your other email address may classify them as junk mail. You should take any necessary steps to ensure that these emails go somewhere you will read them. For example, in Hotmail, if a message goes to the junk mail folder, open the message, click "This is not junk", and select the "mailing list" option. Do not simply add the "from" address to the safe list.
It is very strongly recommended that you do not forward off-campus, and that you instead choose to use IST's Mailservices account.