The Quarantine Plus feature enables you to view messages that have not been delivered to your mail server yet. This can be helpful if your mail server is offline and you want to see who has tried to email you.
Here's how to view pending deliveries:
1) Go to the Quarantine Plus tab in the SpamHero control panel.
2) In the Message Search & Filter box, click on the Show clean messages option and then select Pending deliveries from the drop-down list, as shown here:
3) Click on the Apply filter button to see the messages that are waiting to be delivered.
4) Use the view delivery logs option to view the logs for individual messages and determine why the delivery is being held up:
5) After resolving the issue that is not allowing the emails through, our mail server will eventually deliver all pending messages. Or, you can re-attempt delivery of all pending messages within 15 minutes by going to the Tools > flush mail queue option: