Suppression List

The suppression list prevents the re-sending of an email to a recipient who could not previously be reached for various reasons. As soon as a Retarus MTA receives a bounce the recipient is added to the global suppression list for a maximum of 45 days. If a new delivery attempt is made to a recipient in the suppression list, it is blocked (suppressed). At the same time, the expiry time is reset.

There are three main types of the suppression time (TTL) which means entries can be included in the suppression list varying from 1 day to 45 days depending on the reason returned by the internet-service-provider (ISP). The TTL of suppression type “TEMPORARY_SUPPRESSED” is 1 day meaning the entry is blocked due to temporary issue like mailbox is full. If no suppression reason is returned by the ISP then it will be “PREVIOUSLY_BOUNCED” and it can have TTLs either 7 days or 45 days depending upon the reason returned. 45 days as TTL is configured for reasons like monthly campaigns so same entries doesn’t end up in suppressed list again or reasons like mailbox doesn’t exist.