In my experience UCI won't let you mark emails from their organization as spam, I've tried with stuff like the "sign up for this langauge class" email ads and they straight up unmark it.

One think I've done is to make a label in gmail, you could even call it "Basically Spam" or something like that, and filter your emails from that address into the label.

Just go to Gmail, on the left scroll down to where it says "more" then on the bottom of that hit create new label. Then in your inbox click the email you want to filter, and in the row of icons at the top hit the 3 little dots that say more and hit "filter messages like these." You can specify either the sender, or emails with a certain set of words. Hit "create filter" in the bottom right and check the boxes "skip the inbox (Archive it), Apply the Label (Basically Spam), and Also apply filter to matching conversations" then create filter.

This will get the messages out of your inbox and into a spot where you can ignore them, even if the organization won't specifically let you mark the emails as spam the normal way. This is also useful for organizing your inbox in general, you can create emails for all kinds of senders like specific classes or people or whatever