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Re: Why do so few mail providers support Port 587?

  • From: Eric A. Hall
  • Date: Fri Feb 25 10:38:07 2005

On 2/25/2005 3:16 AM, Adrian Chadd wrote:
> [reposting this to nanog, as my answer might be reasonably ontopic]
> On Fri, Feb 25, 2005, Brad Knowles wrote:
>>At 8:05 AM +0000 2005-02-25, Adrian Chadd wrote:
>>>>	Because your MUA doesn't support SSL on what it considers to be
>>>>non-standard ports?  Because your ISP won't let you set up an ssh
>>>>tunnel instead?  Because there would be no other way to keep your
>>>>mail connection secure, if SSL and ssh are denied to you?
>>>Which MUA, that you/your users are using, won't let you run SSL on port 
>>	Apparently, many Microsoft MUAs don't support that kind of thing.
> Thats strange. I'm sure I've had outlook 200x speak SSL on 587.

The problem with OE (and probably O) is that it only supports SMTP-SSL
carrier sessions rather than StartTLS sessions, especially when alternate
ports are involved. Note that StartTLS is the standard, not SMTPS which
was registered as informational and has been deprecated to boot. If you
are using lots of MS clients, you have to give up on the idea of running
100% encrypted communications over port 587. Not that anybody is stopping
you from setting up TLS-only on 587 and SMTPS on some other port...

Eric A. Hall                              
Internet Core Protocols