FIX: Exchange Online Email Gateway stopped working with Basic Authentication Print ZTN2151 This Zetafax technical note applies to: Zetafax Server version 17.5 and later Exchange Online Windows Server 2012 and later Symptom As part of configuring Zetafax Exchange Online connector you are required to test the connection to your Exchange Online account. When testing the connection an error message is displayed "Connection to Exchange Online Failed. Check credentials and connectivity to Exchange." Or when the Zetadax Server is running there are errors from the email gateway. "Unable to connect to Exchange Online. Check credentials and connectivity to Exchange" This will affect all customers using the Exchange Online email gateway with Basic Authenticaton. Cause The Basic Authentication method (username/password) used previously to connect with Exchange Online has been disabled by Microsoft and has been replaced by the more secure Modern Authentication (OAuth2). Resolution A hotfix is available to resolve this issue. Please contact Equisys technical support for more information. Status This behaviour was corrected in the update detailed above. Last updated: 18th March 2022 (MP/NT) Keywords: Exchange Online, Legacy Basic Authentication, OAuth2 Email GatewayExchange OnlineModern Authentication Related articles FIX: Resolve sign in issues on your Zetafax server when using the Exchange Online Setup FIX: Zetadocs Delivery fails to send after Basic authentication disabled in Exchange Online HOWTO: Use Zetadocs Delivery with Exchange Online INFO: What is new in the Exchange Online Modern Authentication Update FIX: Unable to export more than 1000 email users from Exchange Online