Decommission of SMTP Basic Auth by Microsoft Exchange

As you may be aware Microsoft have announced that they will be retiring the use of Basic auth for Client Submission (SMTP AUTH) in Exchange Online. 

As of an updated timeline published in January 2026, behaviour will remain unchanged until December 2026, at which point Basic Authentication will be disabled by default for existing tenants (administrators will still be able to re-enable it if needed). Microsoft has also stated it will announce a final removal date in the second half of 2027. 

This means that any users of the Hosted platform that are currently using Exchange Online as their mail server will need to migrate to a different platform that continues to support this feature. 

You will need to make this change, if you are still using Microsoft Exchange for your email when they retire SMTP AUTH, we will no longer be able to send out emails via your email server. This will impact new team member invites, voicemail notifications, billing, and any other function that uses your email server to contact your customers. 

While we cannot provide a recommendation for an alternate platform. We are aware that many of our customers utilise transactional email services such as:  Mailgun or Postmark.