Migrating to Office 365 from a On Premise / Hybrid Exchange

Document created by user.oxriBaJeN4 Employee on Apr 14, 2016Last modified by user.oxriBaJeN4 Employee on Mar 27, 2017
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Migrating to Office 365 from a On Premise or Hybrid Exchange requires you to complete a series of steps outlined below. Where possible, the information required is listed on this page. Where a step requires you to perform an external task, or the task is itself complex, a link to another article is provided.

It is recommended you complete the steps in the order displayed below.

Setting Up Your Outbound Email

 

SMTP connectors must be set up to route all your outbound email through Mimecast. See the Configuring Outbound Delivery Routing for Office 365 article for full details.

 

To set up your outbound email:

  1. Create a single outbound connector to Mimecast, adding the following hostnames to the Smart Host section:
    • xx-smtp-o365-outbound-1.mimecast.com (where xx is the region identifier where your account is hosted).
    • xx-smtp-o365-outbound-2.mimecast.com (where xx is the region identifier where your account is hosted).
  2. Check your email flow through Mimecast by clicking the Administration | Gateway | Accepted Email menu item in the Administration Console. Any accepted outbound, inbound, and internal messages are displayed.

 

Setting Up Recipient Validation

It is important that you have completed the recipient validation step before routing inbound mail to Mimecast.

This steps enables us to verify the email addresses to which you receive emails. This ensures only messages destined for valid internal email addresses are accepted. Those that can't be matched against a valid internal address are rejected. To enable use to do this, you have the following options:

 

OptionDescriptionFurther Informtion
Azure LDAP SynchronizationDesigned for customers with or without an onsite Active Directory.Office 365 Azure Active Directory Sync
Directory SyncDesigned for customers who want to connect to their onsite Active Directory.Enable LDAP Directory Sync for Active Directory
Import Users SpreadsheetUser management is manually controlled either through your internal domains, or using a spreadsheet import.Add Multiple Users to Mimecast Using a Spreadsheet Import

 

Setting Up Your Journaling

 

The Mimecast archive allows copies of all internal emails to be extracted from Office 365, and housed offsite in a secure and feature rich environment. With journaling enabled, you'll have:

  • An up to date view of your email (both internal and external).
  • The ability to review and search all emails.
  • Email recovery to your Inbox.
  • The ability to generate full email usage statistics.
  • Individual user access to log in and query their message archive.

 

To successfully set up journaling, you'll have to configure both your Office 365 and Mimecast accounts. See the Office 365 Journalling article for full details.

 

To set up your journalling:

  1. Create a dedicated outbound journal connector using the following journal specific smart hostnames:
    • xx-smtp-journal-1.mimecast.com (where xx is the region identifier where your account is hosted).
    • xx-smtp-journal-2.mimecast.com (where xx is the region identifier where your account is hosted).
  2. Check your email flow through Mimecast by clicking the Administration | Gateway | Accepted Email menu item in the Administration Console. Any accepted outbound, inbound, and internal messages are displayed.

 

Modifying Your MX Record

 

Prerequisite Tasks

 

In order for us to accept your inbound email flow, and deliver it to your organization via the configured delivery routes, you must modify your MX records. However before doing this, it is important that you configure your Office 365 inbound delivery route. This requires you to:

 

Walkthrough

 

To modify your MX record:

  1. Change your MX records to point at the following Mimecast services:
    • MX priority 10 - xx-smtp-inbound-1.mimecast.com (where xx is the region identifier where your account is hosted).
    • MX priority 10 - xx-smtp-inbound-2.mimecast.com (where xx is the region identifier where your account is hosted).
  2. Check your email flow through Mimecast by clicking the Administration | Gateway | Accepted Email menu item in the Administration Console. Any accepted outbound, inbound, and internal messages are displayed.
  3. Allow 48 hours for your changes to propagate through the internet before locking down your firewall (see below).

 

Locking Down Your Inbound Email Flow

 

Read the Locking Down Your Office 365 Inbound Email Flow page for further details.

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