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citpaj
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IIS6 or 7 Virtual SMTP Server - Opportunistic TLS

We run an internal SMTP relay server, on 32-bit standard edition Windows 2003 Server, via IIS6 virtual SMTP server.  We need to turn on TLS for some but not all external recipients.  

I've read that when you enable TLS on the SMTP server bundled with IIS6  the SMTP server will require TLS support on ALL remote hosts it tries to send email to.

Is there any way to enable 'Opportunistic TLS' on this or Windows Server 2008?  That is to say where our server will only send mail using TLS if the remote SMTP server advertises it is capable of accepting it, and will send all other mail normally, to those who don't accept TLS email?
Windows Server 2003Microsoft IIS Web ServerWindows Server 2008

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citpaj

8/22/2022 - Mon
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Yagya Shree

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citpaj

ASKER
From your explanation, I take it that even the Windows Server 2012 IIS/SMTP server can't be configured to use Opportunistic TLS, hence the need to go to Exchange?

If that's the case, then do you know if Postfix supports 'Opportunistic' without the need to manage IP lists for TLS target domains?  I'd prefer to implement Postfix than get back into an MS Exchange solution

Thanks.

Paul.
Yagya Shree

Did you manage to get an answer for your query?
citpaj

ASKER
No answer from the forum, but I found the answer on a web site.  Apparently Postfix can be set up to do Opportunistic.  One of my Uni/Linux guys has built me a Postfix server, configured it to do Opportunistic and I plan to test this shortly.

Given that my initial question was "Is there any way to enable 'Opportunistic TLS' on this or Windows Server 2008" I'll accept your original reply as the solution.  Thanks for the help.
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