There is a 30MB email message size restriction in Awesome Antispam. Any messages over 30MB in size will be rejected. This setting can however be modified in the premium offering but may be restricted if the setting impacts overall performance and reliability of the service.
Content retrieved from: https://support.appliedi.net/kb/a971/is-there-an-email-message-size-restriction-in-awesome-antispam.aspx.