When an email is generated, it is saved on a locally stored messageque, before one of the SMTP servers are contacted.
The message will be sent from the que to the primary SMTP server, and if this fails the secondary will be contacted.
If neither of these respond to the request, the message will be flagged as non-delivered, and tried to be delivered on the next cycle.
This ensures that no emails are lost, due to a network problem or timeout. All email notifications can be tracked through
the mail que screen.