MX record intermittently loses its IP or A records is missing

November 1, 2018 | by iaur | posted as Exchange Online, Mail Flow

Scenario

  • Your tenant is unable to receive emails
  • Senders to your tenant is receiving NDR
  • When you use MX toolbox and found out that your MX does not resolve to an IP address

Re-add the domain

This method is applicable for new tenant or tenant that don’t have any active mailboxes and mail flows yet.

https://docs.microsoft.com/en-us/microsoft-365/admin/setup/add-domain?view=o365-worldwide

Re-trigger domain’s provisioning

Access the link below to re-trigger the DNS provisioning.

https://portal-sdf.office.com/adminportal/home#/homepage

Use the workaround MX

Domain: contoso.com

Example

Affected MX: contoso-com.mail.protection.outlook.com

Workaround MX: contoso-com.mail.eo.outlook.com

Before making any changes, it’s important to use nslookup or an internet web tools against the workaround MX to verify if it resolves to an IP address.

  • Run CMD as admin
Steps
  1. If it does not resolved to an IP, proceed to step 3
  2. If workaround MX resolves to an IP, proceed to use it as a workaround MX for your tenant to have temporary mail flow
  3. Contact Microsoft 365 support to escalate it to their backend team in order to correct the issue