Eric, et. al:
The same *qmail-smtp* program (different instances) listens on all 3
ports (if you have them configured) - the controlling "features" are:
1) the port number listed on the exec line (25, 587, & 465 are the
most common)
2) the status of the REQUIRE_AUTH environment variable (undef or 0
means auth is allowed - it's always allowed - but, NOT required, 1 means
auth will be required)
3) the status of the SMTPS environment variable (undef or 0 means SSL
is allowed - it's always allowed - but NOT required, 1 means SSL will be
required)
NOTE: To get around some ISP's blocking of port 25, some sites actually
use port 26 (an unassigned well-known-port) as an "alternate" SMTP port
- this would be implemented in the QMT exactly as these other ports are
added, except using the different port number.
As I mentioned in my hotwo a moment ago, the ports each have a
"standard" way they're supposed to work:
SMTP (25):
Auth = allowed (not required)
SSL = allowed (not required)
SUBMISSION (587):
Auth = Required
SSL = allowed (not required)
SMTPS (465):
Auth = Required
SSL = Required
As to the port 465 being "depreciated" there is a bit of controversy
over that... originally, 465 was designed to be /the/ SSL port (the same
way 443 is /the /https port companion to the http port of 80) -- BUT
they modified the SMTP protocol to /allow /the use of SSL - even on port
25, so the NEED for a separate port JUST to support SSL became
depreciated... however, several ISPs have started moving towards
REQUIRING their users to use port 465 (and SSL) when sending messages
from off their networks (e.g.: from mobile devices and laptops that may
be connected on other WAN service providers). (Verizon has done this in
some areas, but I don't think all areas yet).
The usefulness of port 465 is no longer in providing the only
SSL-enabled SMTP access anymore -- now its usefulness is in providing
SSL-ONLY SMTP access... which is exactly how Kalil (and Verizon and I
myself) tend to use it...
Dan
IT4SOHO
On 1/20/2012 12:22 PM, Eric Shubert wrote:
On 01/20/2012 10:09 AM, Kalil Costa - Brasilsite wrote:
Guys,
How to configure my qmailtoaster to use port 587 SMTPS Submission for my
clients and port 25 for other servers from internet ? Some like this....
--CLIENTS----- port smtp/587---------------------> **************
* SERVER *
--OTHER INTERNET MAIL SERVERS --- port 25---> * QMAILTOASTER *
* *
--CLIENTS ----- port 25 ----***BLOCKED*** ***************
Thanks for help
Kalz
---------------------------------------------------------------------------------
The stock QMT supports TLS on port 587 for submission, although there
is no way to enforce TLS. Authentication is required though.
SMTPS (port 465) is deprecated, and not implemented in the stock QMT.
If you really need it, there are instructions for implementing it on
the wiki.
I don't know of a way to block clients from using port 25. Never heard
of such a thing, and honestly can't think of a reason why you might
want to do this. If a client uses port 25 and authenticates, I think
the processing is the same as if they used port 587. Someone please
correct me if I'm wrong about this.
