If you are getting a message that says your client has unsubscribed from emails in Matrix
Your client has clicked the link to unsubscribe from emails sent from Matrix.
If they wish to receive the emails again, your client will need to send a blank email to email@example.com. This process could take a few hours to resolve; could be the same day or next day depending on the time of day the email was sent. Once complete, you will be able to send emails to them again and get them set up on new auto-notifications.