How to access a shared mailbox via webmail:
To start, go to CU Denver's resources page:
In the middle of the page, under University Tools, click on Office 365:

Sign into your personal mailbox if necessary using your CU credentials.
Then click on your avatar in the upper-right corner, and click the link "Open another mailbox":

Start typing the address of the shared mailbox in the text box, then pick it off the popup list like in this example:


Then click the Open button and if you have permissions to the mailbox, it will open in a new tab.