certificate for maillists.nottingham.ac.uk has expired

Not directly a Xerte bug/issue, but I noticed that the certificate for maillists.nottingham.ac.uk has expired on Feb 1st 2021. Now I am getting a warning in my browser about the cert not valid (anymore)
Can some webadmin have a look at it? (maybe other certs are expired too)
small suggestion: use a Lets Encrypt certificate. It's easy to deploy and they automatically renew. And they are free.