Microsoft MX Record TTL Support Policy

In regard to a recent announcement from Microsoft, we are informing you of a DNS change that we intend to make on the support policy for the Time To Live (TTL) value for MX records pointing to Exchange Online and Exchange Online Protection.

Microsoft has stated that starting May 2nd 2022, the maximum supported TTL value for MX records will be 6 hours (21,600 seconds) or less for MX records corresponding to domains using Office 365 for email hosting.

  • Exchange Online recommends setting the TTL values to 1 hour (3,600 seconds) but will support values up to 6 hours (21,600 seconds).

This will help your organisation fully benefit from the high availability of Exchange Online by ensuring that email for your organisation is sent to the optimal endpoint in the Exchange Online infrastructure, and it requires some actions on your part.

How this will affect your organisation:

For all MX records corresponding to domains that use Office 365 for email hosting (e.g. vanity domains, accepted domains), We will ensure that your MX record TTL value is configured for a maximum of 6 hours (21,600 seconds) or less.

Performing this action before May 2nd will ensure that organisations that send email to you, have significantly less issues with stale records and will connect to the best endpoint for reaching your organisation.

What you need to do to prepare:

If your DNS is hosted by emPSN, then you are not required to take any actions as we will make all the necessary adjustments for you on the 25th April, ahead of Microsoft’s required date of the 2nd May 2022.

If you use any other DNS provider (ex. ESS/UPDATA) then you will need to take the following steps:

  1. Go to the registrar where you have purchased your domain. (You may need to contact the technical support of the registrar where you have purchased your domain for assistance in changing the MX Record.)
  2. For each Record with Type ‘MX’ that is used for routing mail traffic to Exchange Online:
    • Ensure the record is pointing to your organization’s FQDN for Exchange Online in the mail.protection.outlook.com domain. For example, for the vanity domain contoso.com, the MX record should be: contoso-com.mail.protection.outlook.com.
    • Check if the TTL value is 21,600 or less, if it isn’t, update the TTL to 21,600 or less. We recommend 3,600 for the best experience.


If you have any queries or concerns with the information above please feel free to contact us via support@empsn.org.uk.

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