Mimecast: Configure to allow Mailing List emails.

Mimecast specializes in email security for Microsoft Exchange and Microsoft Office 365.

Why Emails are Blocked

Mailing Lists are a special challenge for software that is trying to stop spam and malware.

Traditionally, Mailing Lists keep the original message sender in the From: header. However, the email is sent from the Mailing List server, not from the original sender's ISP.

Some anti-spam settings will reject emails for this reason.

Mimecast Details

NOTE:
Mimecast is complicated. There are many places within Mimecast to set policies.

Two options to set up a policy allowing Mailing List emails are described below.

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Option 1

  • Navigate to the Gateway / Policies Tab.
  • The policy needs to be created in the “Permitted Senders” category, to allow receipt from your bulk mail provider.
  • Add Mail-List.com's IP addresses to the "Source IP Ranges" field.
    Mail-list.com IP addresses: http://www.mail-list.com/whitelist

See example below to create a new policy:

Option 2

See another example below to create a new policy. This is different way of accomplishing the same result as above.