The Configuration Details of an SMTP Mail Server of a Jira

The configuration details of an SMTP Mail Server of a Jira instance are shown below. The configuration hasn't been changed in the last 24 months. Currently emails are no longer being sent and the failed notifications can be seen in the Mail Error Queue. What is the likely cause of the failure?

A) Email volume has increased and the Timeout is too low.
B) The SMTP password has expired.
C) The user jira has no valid Jira license.
D) The database and/or server disk is full.
E) The Jira license has expired.