Our system is on the front lines when it comes to filtering out spam.  However, our filtering system is very fast.  Once we receive a message we will scan it and classify it as clean or spam within a matter of milliseconds.  So if a message is clean, it will only be on our system for a short time before we attempt to relay the message to your mail server.

If you are seeing messages that have taken longer than this, then there may be a few reasons why:

• If the message is suspicious, our system may trigger the "DeepRush" policy, which is simply a deep filter initiated by our system.  The Deep Filter means that the message is put on hold for a time, and then rescanned later, with new core filtering engine rules.
• A message may be delayed if you have any of the "Deep filter..." policies enabled in the Settings > Filtering Policies tab.
• A message could also be delayed if you have a custom filter setup (in the Settings > Custom Filters tab) that is matching text in the message, and causing it to be deep filtered.
• Also, the Settings > Geographic Policies tab has policies that can deep filter messages anywhere between 15 minutes to 12 hours, depending on the setting.
• If you have the Settings > Catch all enabled (it's enabled by default), this may be causing messages sent to new users on your domain to be greylisted. Greylisting will delay the first message ever sent to the user, but subsequent messages to existing users will be delivered right away. See The catch-all feature for more details.

Hopefully one of these tips can help you troubleshoot any delays you might see.  If not, we can help.  Please provide the To/From/Subject/Date of the delayed message, or the raw message header.  We can then use that information for further troubleshooting.