Re: How to find out if SMTP mailserver supports STARTTLS or (only) SSL/TLS ?

[Jasey DePriest <jrdepriest () gmail com>]

This is a great table. Thanks for sharing it. I'm definitely adding it to
my scanning notes.

-Jasey

On Thu, Oct 26, 2017 at 11:26 AM, Watson, Patrick <Patrick.Watson () ncr com>
wrote:

> There are 4 possible states:
>
> *Service*
>
> *STARTTLS*
>
> *Meaning*
>
> smtp
>
> not present
>
> TLS is not supported at all; everything is plain text
>
> smtp
>
> present
>
> TLS is only supported via STARTTLS. The connection begins unencrypted.
> This is called “Opportunistic TLS”
>
> ssl/smtp
>
> not present
>
> TLS is only supported at the connection level, which begins encrypted.
> STARTTLS is not supported
>
> ssl/smtp
>
> present
>
> TLS is supported at the connection level, which begins encrypted. You can
> also issue a STARTTLS command to turn on TLS, but that doesn’t make any
> sense because it’s already on. Thus, you probably won’t see this often in
> real life.
>
>
>
>
>
> *-- Patrick*
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