May 6, 2025

Exchange Online to Block Basic Senders in Sept. 2025

As managing vice president, Rob Helm covers Microsoft collaboration and content management. His 25-plus years of experience analyzing Microsoft’s technology... more

Exchange Online will block Basic Authentication for SMTP client submission beginning in Sept. 2025.

The change will cut off some mail-enabled document scanners and other devices and applications if organizations do not respond.

To decide how to respond, customers should weigh security, cost, reliability, and reach to recipients outside the organization.

Customers starting now should rely on cloud e-mail services, including other Microsoft services, to get to a solution before the deadline.

Exchange Online will permanently shut down Simple Mail Transfer Protocol (SMTP) client submission with Basic Authentication in Sept. 2025. The change will affect some customer devices and apps that send mail; for example, it might cut off multifunction printers that offer “scan to mail” or a CRM application that sends e-mail alerts to salespeople. Customers will need to update affected devices and apps in the long term, and find alternate delivery methods in the meantime.

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