On Sun, May 01, 2022 at 10:17:33PM -0400, Viktor Dukhovni 
<[email protected]> wrote:

> On Mon, May 02, 2022 at 12:04:13PM +1000, raf wrote:
> 
> > The test email bounced with the following report:
> > 
> > > Diagnostic information for administrators:
> > > 
> > > Generating server: ME3PR01MB8390.ausprd01.prod.outlook.com
> > > Receiving server: ME3PR01MB8390.ausprd01.prod.outlook.com
> > > 
> > > [email protected]
> > > 5/1/2022 12:09:32 AM - Server at ME3PR01MB8390.ausprd01.prod.outlook.com
> > >   returned '550 5.4.317 Message expired, cannot connect to remote
> > >   server(451 4.7.5 Remote certificate MUST have a subject alternative name
> > >   matching the hostname (MTA-STS))'
> > > 4/30/2022 11:59:28 PM - Server at libslack.org (82.134.31.111)
> > >   returned '450 4.4.317 Cannot connect to remote server [Message=451
> > >   4.7.5 Remote certificate MUST have a subject alternative name matching
> > >   the hostname (MTA-STS)] [LastAttemptedServerName=libslack.org]
> > >   [LastAttemptedIP=82.134.31.111:25]
> > >   [SY4AUS01FT024.eop-AUS01.prod.protection.outlook.com](451 4.7.5 Remote
> > >   certificate MUST have a subject alternative name matching the hostname
> > >   (MTA-STS))'
> > 
> > The test email was sent to [email protected].
> > libslack.org's MX record points to smtp10.infotech.no.
> > smtp10.infotech.no's IP address is 82.134.31.111.
> > https://mta-sts.libslack.org/.well-known/mta-sts.txt
> > contains "mx: smtp10.infotech.no".
> 
> That MX host has a self-signed certificate with a name of
> "elrond10.infotech.no", which is rather at odds of the promised support
> for MTA-STS, which requires a Web-PKI trusted certificate with a DNS
> subject alternative name matching the MX hostname.
> 
> The details of the error message may be variously misleading, but that
> does not change the fact that this domain should not promise what it
> does not deliver.
> 
> -- 
>     Viktor.

Good point. This must be what the bounce message is
trying to say.

The MTA-STS wasn't intended. It was a result of using
one of my domains for testing that server (and not
being careful about it). I'll make sure MTA-STS is not
involved at all for the next test. Thanks.

cheers,
raf

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