Re: SMTP SSL on Port Other than 25

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On Mon, 08 Aug 2005 08:17:32 -0700, Mark Olbert wrote:

>>Normally, I would just let this post go by because I don't have enough
>>expertise with MS Outlook to offer a solution. However, your comment on the
>>"idiot system" deserves a comment: it is not an "idiot system". RFC 2821,
>>and its predecessor, RFC 821, describe the SMTP protocol. It is an
>>unauthenticated message transfer protocol, which permits any SMTP client to
>>connect to any other SMTP server to relay email to a destination. Alas,
>>this lack of an authentication mechanism has made it too easy for spammers
>>to subvert the SMTP system for their own purpose.
>>
>>Those who write these RFCs foresaw this problem at least as far back as
>>1998, the date on RFC 2476. This RFC defines a Message Submission system
>>which allows for authenticated connections by Message Submission Agents
>>(MSA), of which MS Outlook is an example, to Message Submission Servers.
>>This system is designed to work on port 587, and may, or may not require
>>STARTTLS (not the same thing as SSL) during the message submission.
>
> The idiotic part is not the requirement for authentication. It's the
> automatic redirection to a different server.
>
> When I look to establish an SMTP connection to port 25 on my.own.mailserver,
> I expect to either (a) get to my.own.mailserver on port 25 or (b) not get
> connected at all (due to network problems, server problems, DNS resolution
> problems, etc.). Silently redirecting me to a different computer than what
> I asked for is "rude" and uncalled for, hence idiotic, IMHO.
>
> I wouldn't even have known what was happening except for the fact that in
> the course of trying to get my secure SMTP connection to work I did a telnet
> my.own.mailserver 25... and found to my shock that the greeting was coming
> from AOL.
>
> My apologies for any confusion I may have caused.

Port 25 is defined by the RFCs for "Message Transfer". RFC 2476 designates
a port for "Message Submission". When you are connecting to port 25, you
are supposed to be an MTA with a message to transfer. If you are connecting
to port 25 for "Message Submission", well, that is now being changed all
over the place. As I mentioned, my ISP, among many others, blocks access to
port 25 for all connections other than to their own mail servers. SBC
customers, mostly, can't connect to GMail SMTP servers on port 25.

That is the way the Internet is moving for handling email. The answer is to
have the mail service providers start using port 587 for "Message
Submission".

--
Norman
~I'll be there, by your side
~in the land of Twilight.
~In your dream I will go
~'till we find the Sunlight.
.

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