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NHSmail- Bring Your Own MX Guide


This short guide provides an overview of the NHSmail Bring Your Own Mail Exchange record (BYO-MX) solution. This solution is primarily provided for organisations migrating from their local on-premise email services to NHSmail and want to enable their users to continue to receive emails on their legacy email addresses for a period.

When an organisation migrates to NHSmail, their email address will change from their current username@organisation.nhs.uk to username@nhs.net (and sub-domain equivalent). This means that any emails sent to the legacy email address will not be received by users without a cutover solution in place. BYO-MX enables a more graceful cutover and enables communications to be routed from the legacy email address to the new NHSmail inbox.

Solution Summary

Any organisation migrating to NHSmail will be able to cutover their MX record to the NHSmail service. Once migrated to NHSmail, each user will have their legacy email address mapped to the NHSmail account as an alias. The organisation migrating to NHSmail will need to ensure that their local DNS Team change the value of their MX record from the on-premised mail server to NHSmail. The configuration required to do this will be provided by the Accenture Team at the appropriate cutover point.


The BYO-MX solution will be in place for a period of 6 months only following the migration. After this your old domain/s will be removed from the relay and only the primary @nhs.net accounts will be used. Extensions are by exception only and if agreed will be for a maximum additional 3 months, NHSmail reserves the right to reject requests without appeal. To request an extension please provide justification and information to feedback@nhs.net.

Solution Limitations

The limitations of the solution are outlined below:

  • Only 1 single MX record (i.e. the primary organisation.nhs.uk only) for each migrating organisation. If more are required, organisations should contact NHS England (feedback@nhs.net) who will review the impact on the NHSmail service.
  • The BYO-MX address will be applied as a secondary email address. The purpose is to continue to receive email only. The primary email address will always be the user’s @nhs.net email address.
  • The BYO-MX solution is only available to users who have been migrated to NHSmail from the legacy on-premise service. Any new users created on NHSmail following the migration will not be in scope for the BYO-MX solution.
  • After BYO-MX has been fully adopted and subdomains removed from the relay Accenture will ask NHS England to remove the trust original MX record from HSCN and Internet DNS.

The NHSmail team will notify a designated LA/PLA within your organisation, 14 calendar days before expiry of the MX record solution. It is the responsibility of the requesting org to ensure that expiry dates are captured and factored into your migration schedule.

Last Reviewed Date 03/02/2023
Updated on 03/02/2023

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