Provide notifications to Jira Admins when there are connectivity failures on incoming mail server

Currently, when there's any connectivity issues from the Incoming Mail Handler to the configured Mail Server, there are no alerts to the Jira Admin. Which adds a risk of losing new requests that are sent via Incoming Mail.

Jira should send a notification email to Jira Admins as soon as it detects the connectivity issue; that way, the customer can connect and rectify the issue and avoid missing new requests sent to the incoming mail server.