Default Mail Queue Retention Policy
Email is kept in the mail queue for 30 days, during that time we are attempting to deliver your email to the MX record that is configured for your domain.
When mail exceeds 30 days in the queue it is set with a Non Delivery Notification and cannot be recovered.
Expanded Mail Queue Retention Policy
If you require your mail retention to exceed 30 days we have an optional 45-day retention option. Please contact support for more information.
Spam Messages in the Queue
As mentioned the retention policy for email is 30 days and by default all our accounts have spam filtering enabled. If however you disable your spam filtering or reduce it to a level where we are accepting Spam messages or if email is whitelisted and then is being deferred by your mail server rather than accepted we will delete spam messages in the queue after 5 days.
The messages to be deleted will have a SpamAssassin score greater than 5 and a Cyren score of SPAM.
Oftentimes a customer will run spam or virus filtering on their local mail server as well as utilizing our cloud based spam filter. When this happens there may be a situation where we have accepted emails based on your filtering policy but are unable to deliver the messages to your mail server, even though you mail server is online and is accepting genuine messages. This often happens when the mail servers policy is to defer spam messages rather than rejecting them, which means that even though your primary mail server is online we end up with spam messages in the queue that we would have attempted to deliver over 200 times over a spam of 30 days.
These messages are essentially in limbo, your mail server will not accepted the messages but they are also not being rejected. These queued messages will cause delays for your legitimate email because our servers are programmed to only open a limited number of simultaneous connections (slots) to your mail server to deliver email. If there are a few hundred or a few thousand spam messages in the queue and we are retrying them, these retries occupy a deliver slot and may inhibit new messages from being delivered in real time.
Your mail server should respond with a 500 error message to email that violates your corporate spam policies, and not a 400 deferral.