This article contains information regarding the email retry schedule for possible delayed emails within the Email Security.Cloud service.
Symantec Email Security.cloud
Symantec's .Cloud MTA uses an exponential retry schedule based on a retry interval of 400 seconds.
The actual retry time that is used on each attempt of a message is in the range of -30 seconds to +30 seconds from the value shown.
This schedule means that after the first day of a mail being in retry, there are only four further delivery attempts for the duration of the schedule. This schedule differs slightly from the old retry schedule, which had more retries throughout the schedule. The new schedule means that if a client’s mail servers are down for two days and then brought up again, they will not receive any of the queued mail for a further day.
Then every 12 hours, until email is delivered or expired. 7days or 21times