There's not really a way to opt out of using the spam filter, but users do have the ability to tune how aggressively the filter behaves on mail sent to you.  In your user directory, there is a hidden directory named .spamassassin, and Inside of that is a text file called user_prefs (there are other files too, but you should leave those alone).  Using a text editor, you can add one of the following lines to the end of the file:

• whitelist_to {your email address}
• more_spam_to {your email address}
• all_spam_to {your email address}

These choice are list in order of how much spam will be allowed through the filter, where the first will be a fair amount, the second will allow most spam through, and the third will let in all but the most egregious spam.

​If you are turning off the spam filter because you have found it to be making mistakes (either false positive or false negative), please email nospam@cs.utexas.edu --we want to know!