Situation:
1. Create mail server, leave default From: field (${fullname} (Confluence) )
2. Create a user, set him to have daily digest mail notification.
3. Make a change
4. Scheduled Jobs> Run "Email Daily Reports"

Expected behavior:
Created user receives an email from (Confluence)

Actual behavior:
Created user recieves an email from Anonymous (Confluence)

Reason:
${fullname} resolves to Anonymous when null.

Reason it's problematic:
Many mail filters will filter as spam when from is Anonymous.