Shared Mailboxes keep asking for password in Apple Mail
I'm using Apple Mail to access my M365 work email account and also have several associated shared mailboxes.
I've set the shared mailboxes up as follows -
Username: my M365 email address/shared mailbox email address
Password: my M365 email password
Host Name: outlook.office365.com
Automatically manage connection settings is checked.
Each time I lock my Mac and then return Mail prompts me for the password, which I enter as above and the mailbox works, however it's getting annoying to have to do this every time I leave and come back to my Mac.
Using an MBP 2018, Big Sur.
Thanks in advance to anyone who can help with this. It's infuriating!
MacBook Pro with Touch Bar