Send failed reload notifications via email

[mountaindude]

Sending such notifications using Slack or MS Teams is great, but for companies with email driven workflows the IM channels are a complement, not the main notification channel.

Enhance the current, basic setup for email notifications (which use log4net log appenders) with features such as

• Templating for email subject and body. This makes it possible to dynamically inject info from the failed reload into the email message
• Rate limiting. Don't spam users with email notifications.
• Include script logs in notification emails.
• Flexibility wrt configuration of smtp/email servers.
• Set email priority flag
• Multiple recipients
• Links to QMC/Hub from within the notification email