Thank you to staff and students for your patience while we resolved the issue with @lists.bath.ac.uk. We have identified the cause.
If you continue to have issues with sending emails to @lists.bath.ac.uk in Outlook client please take these steps to clear your global address list.
If you continue to have problems with sending to @lists.bath.ac.uk you can log a ticket
Outlook Web App (OWA)
You can also use OWA to send emails to @lists.bath.ac.uk. You can login to mail.bath.ac.uk.