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SMTP TLS partial? RRS feed

  • Question

  • We secured our outbound email with TLS, and forcing it mandatory on certain domain.

    Now our partner is asking whether by enforcing SMTP TLS, whether the whole email is encrypted with TLS during the transport or just the message body?

    She is asking this because when analyzed on email header, the subject of the email is displayed in clear text. It just makes no sense to me that email transport has the preference of choosing whether to strip down certain parameter to be displayed in clear; while the other is encrypted.

    I always thought that with TLS on the transport, the mail transfer server will start sending the whole message (including subject, body, and attachment of the said email) via TLS.

    Forgive me as I've found no article on this. Hopefully it's a general question that can be asked here.

    Thank you in advance for any help to clarify this issue to me :)


    ---Pat


    Thursday, May 11, 2017 4:13 PM

Answers

  • You mean the whole email would be encrypted?

    ---Pat


    The whole SMTP conversation would be, not the email. There's a difference.
    Saturday, May 13, 2017 11:32 AM
  • When you use TLS encryption, the SMTP session from your mail server to the next hop is encrypted. The concept of encrypting the actual E-mail itself would be called as S/MIME. To answer your question, the E-mail would be sent after the TLS session has been established.
    Thursday, May 11, 2017 9:13 PM

All replies

  • When you use TLS encryption, the SMTP session from your mail server to the next hop is encrypted. The concept of encrypting the actual E-mail itself would be called as S/MIME. To answer your question, the E-mail would be sent after the TLS session has been established.
    Thursday, May 11, 2017 9:13 PM
  • You mean the whole email would be encrypted?

    ---Pat

    Saturday, May 13, 2017 10:58 AM
  • You mean the whole email would be encrypted?

    ---Pat


    The whole SMTP conversation would be, not the email. There's a difference.
    Saturday, May 13, 2017 11:32 AM
  • Hi Pat,

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    Thanks for your understanding,

    Regards,


    Niko Cheng
    TechNet Community Support


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    Thursday, May 25, 2017 10:09 AM