Support » Plugin: WP Mail SMTP by WPForms » Microsoft Algorithm Change Broke Plugin

  • Resolved libertytalk


    Hello, the plugin just suddenly ceased working on Monday, January 12, 2020. No site updates reconfiguration made since January 3, 2020.

    While looking for a solution, came across the following statement from Microsoft:

    Beginning November 1st, 2019, Office 365 is slowly turning off the TLS cipher algorithm 3DES. If you are using devices or applications that only support 3DES, TLS will start failing. As TLS is mandatory for the SMTP AUTH client submission (also known as Authenticated SMTP or SMTP AUTH for short), you may experience emails no longer sending. You will need to upgrade or update all of your devices and applications to use the new TLS version and ciphers.

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  • Plugin Author Slava Abakumov



    WP Mail SMTP plugin does not modify or control the way an SMTP connection is established. This is done by WordPress using whatever is available for it on a server, that’s the server that actually creates a connection.

    So, 3DES algorithm usage is controlled by a server (and its configuration) that connects to the Microsoft SMTP server. With that said, you may want to contact your hosting support to make sure they are not using 3DES algorithm when signing all the outbound requests to SMTP servers.

    Have a good one.

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