Microsoft blocking Tutanota users from Teams registration, claims fix unfeasible

The Microsoft Teams logo is shown on a smartphone, with the Microsoft logo displayed in the background on a wall

German email provider Tutanota has publicly called out Microsoft for allegedly blocking users using Tutanota email addresses from registering a Teams account.

The company had discovered that anyone who attempts to sign up for Microsoft Teams with a Tutanota email address is shown an error message reading “[email address] hasn’t been added to your organization’s directory. Contact your admin or try a different email.”

Tutanota has been in a back-and-forth with Microsoft for weeks over the issue, but was repeatedly told by Microsoft that it is “currently not feasible for the domain to become a public domain”.

Disputing this claim, Tutanota has taken the issue to the public and accused Microsoft of engaging in an anti-competitive practice.

With millions of users worldwide, the company maintains that its customers have a right to privacy that should not be compromised through a requirement to use a secondary email provider.

The problem, according to TechCrunch, appears to be linked to the fact that Teams recognises Tutanota addresses as corporate emails, hence the request for denied users to contact their administrator.

At the time of writing, IT Pro has been informed, that emails using the Tutanota domains and now work with Teams registration. This follows a Twitter exchange that the company believes improved the situation behind the scenes.

Three other domains,, and, remain blocked.

"To us it is very frustrating that such a step is needed to get an issue resolved by Microsoft. In our view it is negligence on Microsoft's part that does result in antitrust issues,” said a Tutanota spokesperson.

Unlike many email providers, Tutanota encrypts its entire mailbox and address book and allows users to send end-to-end encrypted emails to any email address via the use of a password. For these reasons along with a whole host of other privacy features, it is considered one of the most secure email services available.

“This severe anti-competitive practice forces our customers to register a second email address – possibly one from Microsoft themselves – to create a Teams account,” said Tutanota co-founder Matthias Pfau, in a blog post.

“When asked to change the current situation, a spokesperson for Microsoft simply said it would not be possible for them to allow people to register a Teams account with a Tutanota email address. Period. We repeatedly tried to solve the issue with Microsoft, but unfortunately our request was ignored.”

IT Pro has approached Microsoft for comment.

Rory Bathgate
Features and Multimedia Editor

Rory Bathgate is Features and Multimedia Editor at ITPro, overseeing all in-depth content and case studies. He can also be found co-hosting the ITPro Podcast with Jane McCallion, swapping a keyboard for a microphone to discuss the latest learnings with thought leaders from across the tech sector.

In his free time, Rory enjoys photography, video editing, and good science fiction. After graduating from the University of Kent with a BA in English and American Literature, Rory undertook an MA in Eighteenth-Century Studies at King’s College London. He joined ITPro in 2022 as a graduate, following four years in student journalism. You can contact Rory at or on LinkedIn.