Mimecast Email Continuity Planning

There are two primary scenarios in which having an email continuity plan involving Mimecast is essential:

Scenario 1: Mimecast Experiences a Prolonged Outage

Scenario 2: Your primary email service (e.g., Office 365, Gmail, hosted, or on-premises) experiences a prolonged outage

Note: The Mimecast Continuity feature is specifically designed to assist with Scenario 2.

We recommend maintaining documented procedures for both scenarios. Our team can assist in creating and customizing this documentation for your environment.

Scenario 1: Mimecast Outage

In the event of an extended Mimecast service disruption, take the following steps to re-route email and maintain operations:

• MX Records:
  Update your DNS records to point away from Mimecast and directly to your online email service.

• Inbound Exchange Rules:
  Disable Inbound Lockdown to allow email from sources other than Mimecast.

• Outbound Exchange Rules:
  Disable the Mimecast outbound connector so mail can be sent directly to recipients without routing through Mimecast.

• Security Considerations:
  Removing Mimecast from your mail flow disables its security features. Ensure that native email security controls (e.g., Office 365 Defender, SPF/DKIM/DMARC) are enabled and configured appropriately.

Scenario 2: Primary Email Service Outage

When your main email platform is down, Mimecast serves as the interim interface. Key steps include:

• Routing Considerations:
  Prevent email from continuing to route to the downed environment. Mail servers will retry delivery for up to 30 times over 4 days before returning a non-delivery report (NDR) to the sender.

• User Access & Communication:
  Enable access and train users on how to access their email via the Mimecast Personal Portal or supported applications.

• Authentication Setup:
  Ensure a unified authentication method is in place (e.g., SSO, cloud identity provider).

• Folder Availability:
  Consider enabling Sync & Recover or using Mimecast MSE to replicate user mail folders for continuity of access.

This guide offers a foundational approach to continuity planning. Your specific configuration may require additional steps or customization. Please contact us for personalized assistance.