How do I control the retry intervals in the SMTP outgoing queue?

The Outgoing queue for sent mails from the Merak Mail Server is controlled by:

  • file \Merak\Config\interval.dat (if it exists)
  • Undeliverable Warning after X hours

The first attempt at delivery is always just after the message enters the queue.

The default retry intervals (if no interval.dat file exists) are as follows:

  • Retry # 1 - 2 minutes later
  • Retry # 2 - 10 minutes later
  • Retry # 3 - 38 minutes later
  • Retry # 4 - 70 minutes later
  • Retry # 5 - 120 minutes later
  • Retry # 6 - 120 minutes later
  • Retry # 7 - 120 minutes later
  • Retry # 8 - 120 minutes later

After the 8th retry, the same retry interval will be used until the undeliverable after (Days) threshold is reached (Set in Mail Service -> SMTP Service -> Delivery tab)

If you wish to set your own retry intervals you should create or modify the file interval.dat in the Merak\Config\ folder.

The file should consist of 8 lines, each with a single value for the next retry.

For example -

Interval.dat

1st retry at 5 minutes (=5)

2nd retry at 5 + 5 minutes (=10)

3rd retry at 5 + 5 + 10 minutes (=20)

4th retry at 5 + 5 + 10 + 15 minutes (=35)

5th retry at 5 + 5 + 10 + 15 + 60 minutes (=95)

6th retry at 5 + 5 + 10 + 15 + 60 + 120 minutes (=215)

7th retry at 5 + 5 + 10 + 15 + 60 + 120 + 240 minutes (=455)

8th retry at 5 + 5 + 10 + 15 + 60 + 120 + 240 + 300 minutes (=755)

Then a retry every 300 minutes (1055, 1355, 1655 etc.)

The default Undeliverable Warning after can also be changed in Mail Service -> SMTP Service -> Delivery tab.

SMTP Server - Delivery Tab - Undelivery

Note that for certain "immediate" errors these retry values are ignored and Merak retries after 6 hours. If this retry fails a message is sent to the sender informing him of the problem but Merak keeps retrying for 4 days. If the message still cannot be sent, the sender is informed.