Hi Axel,

 

In order to manage the spool you need to be logged in as the System Administrator. Then click on the Manage icon on the left. The first setting in the list is a Spool folder, where you can find all messages or just those waiting to deliver. This help document details what you'll find: Spool.

 

If you don't have the System Administrator login credentials, you are likely using a hosted account. In that case, you would need to contact whoever manages your installation.