Re: Multiple Virtual Server Problems

  • From: "A. M. Salim" <msalim@xxxxxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Wed, 3 Nov 2004 08:47:35 -0500 (EST)

Hello Mustafa,

> Sure you can define multiple POP3 virtual servers for the same IP address.
> It is important the unique port and IP combination. For the first virtual
> server you will have, for example, the IP address and the only
> port 110. And the second virtual server will have the same IP,
> but a different port 995. This will function in each primitive
> mail/messaging server. I think Exchange 2003 is not a primitive messaging
> system, or is it?

As I stated in my email, you can set up multiple SMTP's on the same IP
provided you are prepared to use non-standard ports.

So what's the big deal with using non-standard ports?  Not much for POP3
as long as you know how to configure your Outlook to use a port other than
110 for POP3.

But it is a MAJOR deal for SMTP.  Using non-standard ports for SMTP will
prevent any other mailserver from sending you email if they do not know
which port to talk to your server on SMTP.  Since there is no "public
query, LDAP or database" or any other standard method for figuring out
which SMTP port you are using (if not port 25), you will be reduced to
receiving email only from those mail servers who know that you are using
port 995 (or whatever port you pick) for SMTP.  The sending mailserver
will not automaticall figure out, somehow, that you are using port 995
unless you tell it so (by a phone call or memo to the system admin and
he/she is nice enough to accommodate your non-standard port, most
unlikely!).  You will receive no email from hotmail, yahoo, aol,
earthlink, rr, or any other mailserver who does not share knowledge of
your secret port 995 and is willing to reconfigure their mailserver to
send to port 995 just for you.  Probably not a good thing!  (This is true
regardless of whether the remote sending mailserver is an Exchange server
or non-Exchange Linux or other mailserver).

best regards

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