MX records or Mail Exchange records are DNS records used to direct emails to the mail server. When you send an email from your Exchange, Office 365, or any other email account, the MX records indicate how the email will be routed in accordance with the SMTP or Simple Mail Transfer Protocol- a standard protocol for emails.
It contains two pieces of information,
- The domain name where the server is hosted
- Priority Number indicating the order in which server will receive emails (starts from ‘0’)
After migrating your Exchange on-premises server or setting up a Hybrid Exchange environment, you must configure and change the MX records to point to Office 365. This step comes after you have added the domain in Office 365.
In this guide, we discussed steps to add or update the MX records in Office 365. We have also discussed methods to check if the Office 365 MX records are successfully changed.
Steps to Update MX Records to Office 365
Unless you change or update the MX records to Office 365, the inbound mail flow to on-premises Exchange will be interrupted. To resolve this, you must point the MX records to Exchange Online or Office 365.
The steps are as follow,
Step 1: Find and Copy Office 365 MX Record
- Login to Microsoft 365 and navigate to Setup> Domains.
- Click on your default domain and copy the MX record address value.
TIP: If the domain is not connected, go to Settings> Domains, click on the added domain, and follow the wizard to find the MX records.
Step 2: Update MX Records to Office 365
- Now login to your domain registrar, such as GoDaddy, or wherever you purchased the domain name and open the DNS management settings.
- Find the MX record pointing to your on-premises Exchange Server and remove them.
- Add a new MX record and paste the MX record address value you copied earlier from Office 365 admin center in the Points To box, type @ in Host, 0 in Priority as shown in the below screenshot.
- In TTL (Time to Live), choose or add a value of 5 or 5 min.
- Save the changes.
TIP: Change your existing TTL to 5 minutes a few days before changing the MX records to Office 365. This will boost the DNS propagation and update the MX records faster.
Step 3: Verify Office 365 MX Records
Once you have updated or changed the MX records to Office 365, use web tools, such as MxToolbox or WhatMyDNS, to verify if the MX records are updated successfully.
The steps are as follow,
- Open the web browser and go to WhatMyDNS.
- Enter the domain name in the box, choose MX from the drop-down, and click ‘Search.’
- Check the MX records value. It should be pointing to Office 365. If not, wait for a while and then check again as DNS propagation takes a while to complete.
You may also enter your domain name at MxToolbox to check the MX records are updated successfully.
Verify MX Records via Message Header Analyzer
You may also check the MX records are updated and working by analyzing the Message Header using Microsoft Message Header Analyzer. It will help you detect if the emails sent and received are delivered through the Office 365 or Exchange on-premises server. The steps are as follow,
- After updating the records, send an email from your Outlook to your Gmail account and then send an email from Gmail to your Outlook.
- Double click on the sent message to open it in a pop-up window and then go to File>Properties
- Copy the content displayed in the Internet headers box.
- Visit Microsoft Message header Analyzer and paste the internet header content
- Click Analyze headers
Check the Submitting Host and Receiving Host for Office 365 MX records.
In this article, we showed you the steps to update MX records to Office 365. We also discussed steps to verify that the MX records are pointing to Office 365 using web tools and Outlook. If you plan to migrate your on-premises Exchange Server to Office 365 (full or hybrid migration), you can use an EDB converter tool to move mailboxes from your on-premises Exchange Server to Office 365 in a few clicks. The software can help expedite the migration process and prevent any data loss. You can also use the software to take local backups of your mailboxes in PST format.