The university policy on password sharing is very clear. Do NOT share your passwords with anyone. You should also always be sure to use a strong password and change it regularly (at least once a year). It's also worth a reminder that you should never give your password out over the phone or on an unknown website. Be sure to check the URL (at the top of the browser window) to be sure you're at the web site you expect.
In the event of an emergency (illness, personnel issue, etc), we have a procedure to get access to emails, Cybox, Qualtrics, and computers, if necessary.