On Wed, 2008-05-14 at 21:53 +0300, Aidas Kasparas wrote:
> Why do you think it is not possible in general?
>
> >From technical point of view, server allways provides ESMTP response to
> STARTTLS command. This command can have limited set of reply codes
> {220,501,454}. Only first of them says that TLS negotiation should
> start. So, technically it is possible to distinguish cases.
>
> As to why host should advertise TLS capabilities and later refuse to use
> it. Mis/under-configuration is one (if software detects this in lazy
> way). Lack of resources at the moment of STARTTLS command is another
> (load too high at the moment, TLS-accelerator is full, etc).
>
> I do not have arguments why courier should not fallback in 454 cases
> [remember "be liberal at what you accept" internet principle?].
By design and intent, Courier is more strict in it's observance and
enforcement of relevant RFCs than many other MTAs. Similarly, some MTAs
will resolve and use an MX resource record given as an IP address. Such
resource records violate RFC 1035 and Courier will declare an error on
any MX lookup with returns an IP address instead of a domain name and
will refuse to proceed.
There are enough problems out there with non-conforming mail clients.
Often people don't have a lot of choice in this regard. System
administrators, on the other hand, have the ability to compel standards
compliance on their mail systems and there's little or no excuse for
running a mail server that advertises a capability that it doesn't
support.
--
Lindsay Haisley | "In an open world, | PGP public key
FMP Computer Services | who needs Windows | available at
512-259-1190 | or Gates" | http://pubkeys.fmp.com
http://www.fmp.com | |
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
courier-users mailing list
[email protected]
Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
