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CulverITGuy's avatar
CulverITGuy
Brass Contributor
Jul 02, 2024

Did Microsoft start blocking non TLS emails?

I'm starting to get complaints about external emails being rejected with the error: Remote host said: 454 4.7.0 Connection is not TLS encrypted. Recipient organization requires TLS.

 

This appears to have started on 6/27/2024. I haven't made any recent changes, so it seems like a change on Microsoft's end?

  • chrisslroth's avatar
    chrisslroth
    Brass Contributor
    Can you please check if your Outbound-Connector enforce TLS.
    The recipient mailserver reject your mail, because you don't send TLS-encrypted.
    • CulverITGuy's avatar
      CulverITGuy
      Brass Contributor
      Yes, that's my server (Microsoft) rejecting emails because they are not TLS-encrypted. That is the error message the sender is getting. We were receiving non-TLS emails util the 27th, then they stopped coming through.
      • chrisslroth's avatar
        chrisslroth
        Brass Contributor
        Check on the senders server if the outbound connector enforces TLS. If this is the case TLS-encryption is active and should work. Otherwise you have to contact microsoft maybe there is an issue in MS-datacenter

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