Your administrator has policies in place that place messages on hold. These could be based on spam, attachment, or content examination policies, designed to prevent unwanted emails from reaching your inbox.
The Personal On Hold viewer at https://login.mimecast.com allows you to view the emails that have been held, and decide if you want to release them or reject them, individually or in bulk.
Select the Advanced icon. (Three dots) Select Personal On Hold from the menu Select either a single email or multiple emails Using the Release icon, select one of the following desired actions: Release Email, Release Email & Permit Address, Release Email & Permit Domain.