How to configure Mimecast to allow Mailing List emails through
Mimecast specializes in email security for Microsoft Exchange and Microsoft Office 365.
Mailing Lists are a special challenge for software that is trying to stop spam and malware.
Traditionally, mailing list keep the original sender of the message in the From: header. However the email is sent from the mailing list server, not from the normal ISP that the sender usually sends all email from.
Therefore, some anti spam settings will reject emails for that reason.
Mimecast is complicated, there are a lot of places within Mimecast to set policies.
You need to be in the Gateway / Policies tab
The policy needs to be created in the “Permitted Senders” category
For allowing receipt from your bulk mail provider