Re: [ietf-smtp] own mail server: DNS / static IP / no bad reputation?

Arnt Gulbrandsen <arnt@gulbrandsen.priv.no> Mon, 12 October 2020 11:16 UTC

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From: Arnt Gulbrandsen <arnt@gulbrandsen.priv.no>
To: ietf-smtp@ietf.org
Date: Mon, 12 Oct 2020 15:53:42 +0200
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Subject: Re: [ietf-smtp] own mail server: DNS / static IP / no bad reputation?
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On Monday 12 October 2020 13:04:17 CEST, Sam Varshavchik wrote:
> On Mon, Oct 12, 2020 at 3:34 AM Claus Assmann <ietf-smtp@esmtp.org> wrote:
>> If STARTTLS is used, they shouldn't be able to do it, unless they
>> mess with SMTP (or much worse: with TLS), right?
>
> They intercept outbound port 25, and simply don't advertise STARTTLS.
> Only STS will catch that.

See https://toroid.org/vodafone-smtp-mitm for example. Vodafone India makes 
it so that when mobile phones connect to SMTP servers outside Vodafone's 
network, they simply don't receive any STARTTLS advertisement.

Arnt