Email Security Cloud Gateway - Domain Authentication for Microsoft Exchange Online EOL - May 2022

Service Update

Availability	May 22nd, 2022
Product(s)	Email Security Cloud Gateway
Who's affected	Email Security Cloud Gateway, Administrators

Overview

Microsoft recently announced their deprecation plan for Basic Authentication to Exchange Online.

While Microsoft has extended the deadline for Basic Authentication's end-of-life to December 2022, Mimecast will still end its support for Basic Authentication on October 1st, 2022

What's changing

From early 2022, Mimecast applications configured to use the Domain Authentication Mechanisms of Microsoft 365 may experience authentication problems due to the deprecation.

Affected Mimecast applications are: 

• Mimecast Administration Console. 
• Mimecast for Outlook. 
• Mimecast Personal Portal.
• Mimecast Web Security Agent (Windows and Mac).
• Mimecast Mobile App (Android and iOS). 
• API integrations. 
• Mail clients are configured to retrieve messages from Mimecast using POP. 
• Mimecast Connect Application. 
• Mimecast Synchronization Engine (MSE). 

Recommended actions

To ensure a continuation of service, review the authentication methods configured on your Mimecast account. In addition, Mimecast advises customers to migrate to a secure, token-based Modern Authentication protocols, such as SAML. 

Frequently Asked Questions

Q:	Can I check which authentication methods are active on my Microsoft tenant?
A:	Microsoft has provided the ability to check the security settings on your tenant using the Microsoft self-service tool. Run the test on your Microsoft tenant.
Q:	Can I opt-out of this change?
A:	Microsoft has provided a limited opt-out using the Microsoft self-service tool.
Q:	What are the timelines?
A:	Beginning in 2022, Microsoft will start selectively picking tenants and disabling Basic Auth for all affected protocols except SMTP AUTH for 12-48 hours. During this time, all clients and apps that use Basic Auth in the selected tenants will be affected, and they will be unable to connect. Any client or app using Modern Auth will not be affected. On October 1st, 2022, Microsoft will begin to permanently disable Basic Auth in all tenants, regardless of usage, except for SMTP Auth. While Microsoft has extended the deadline for Basic Authentication's end-of-life to December 2022, Mimecast will still end its support for Basic authentication on October 1st, 2022
Q:	What is Mimecast doing for new customers who are still using the Connect Application?
A:	To avoid new customers connecting to Mimecast and creating Authentication Profiles to Microsoft 365, guidance will be updated in this article, Connect Application - Setting Up User Authentication.
Q:	How do I know if my API integration is going to be affected?
A:	API integrations that currently run as a user and are configured for Microsoft 365 will be affected. Review the authentications configured for the API user account to resolve this and change to a different authentication method.
Q:	How do I review and update my authentication methods in Mimecast?
A:	Authentication methods can be configured by navigating to Administration | Services | Applications | Authentication Profiles. Additionally, full details can be found in the Configuring Two-Step Authentication Profiles article.
Q:	How do I know my changes have been effective and that I am now safe from the Microsoft EOL?
A:	Once you have migrated your Microsoft 365 authentication methods, contact Mimecast support or your Customer Success Manager, who can confirm you will no longer be affected.
Q:	I am a new customer; what authentication method should I configure?
A:	New customers should configure a token-based authentication method, e.g., SAML.
Q:	Does Mimecast support authentication methods other than SAML?
A:	Yes, we do. Mimecast supports several different authentication methods across all our applications. These methods are listed on the Authentication Guides page.
Q:	How do I identify if I am affected?
A:	A notification on your Mimecast account will inform you if you are affected and what action is required.
Q:	I am a customer administrator; How do I obtain a list of affected users?
A:	Contact your Customer Success Manager, who will be able to provide you with these details.
Q:	I am a partner - How do I identify customers that need to make changes?
A:	Contact your Partner Account Manager, who will be able to provide you with these details.