Messages queued for known valid recipients because of temporary problems with the destination route (for example network problems) are automatically retried for delivery at the following approximate intervals:
- during the first 2 hours, delivery is retried at a fixed interval of 15 minutes.
- during the next 14 hours, delivery is retried at a variable interval, starting at 15 minutes and multiplying by 1.5 with each attempt (e.g. after 15 minutes, then 22.5 minutes, then 34 minutes, and so on).
- 16 hours since the initial failure, until 4 days have passed, delivery is retried at a fixed interval of every 6 hours.
- after 4 days we generate a bounce to the sender. If the bounce cannot be delivered immediately, it will be frozen. After this time, the delivery of the message will have permanently failed. Optionally via the Software API, the 4 days can be overruled to a longer (or shorter) period.
When a message is frozen, (when a message can neither be delivered to its recipients nor returned to its sender) no more automatic delivery attempts are made.
A super administrator can “thaw” ( force retry) such messages when the problem has been corrected.
SpamExperts caches valid recipients for up to 4 days.
When such an entry has expired, SpamExperts will not queue email for such recipients and instead temporarily reject the message so it's queued on the sending server.
The sending server in such a case will automatically retry delivery.
When using the "Local Recipients" feature, no caching is involved and SpamExperts continues to accept and queue the emails for all specified recipients.
