On the Management > Notifications > Global tab you can configure the sender address (i.e., the From address) to be taken for notification emails sent by Sophos UTM. By default, this is email@example.com. If you want to change this address, it is advisable to enter an email address of your domain, as some mail servers might be configured to check whether a given sender address really exists.
Limit notifications: Some security-relevant events such as detected intrusion attempts will create a lot of notifications, which may quickly clog the notification recipients' email inboxes. For this reason, Sophos UTM has sensible default values to limit the number of notifications sent per hour. If you disable this option, every security-relevant event will create a notification, provided the event is configured so as to send a notification on the Management > Notifications > Notifications tab.
Here you can enter a description of Sophos UTM, e.g. its location, which will be displayed in the notifications sent.