What happens if the mail server goes offline?

Question
What happens if the mail-server is temporarily disconnected?
Answer
In case the e-mail could not be delivered on the mail-server(s), Spamexperts will retry it according to the standards.
The following scheme is used for this:
During the first 2 hours, every 15 minute the delivery is retried
The next 14 hours, this interval is increased with a factor of 1.5 (15 minutes, 22½ minutes, 34 minutes, ...)
Then, delivery will be retried every 6 hours
If after 4 days the e-mail could not be delivered, the sender will be informed
If the mail-server has a short downtime, most messages will be received within 15 minutes. When the server has a longer downtime, delivery can be delayed some longer.
E-mail only permanently bounces if the receiving mail-server is not available for 4 days.
 
 You can see in the Delivery queue in the Spamexperts control panel which e-mails have not yet been delivered, and for what reason.