I see what you are trying to do. However, I think you will run into = more trouble if you could actually do that. XMail needs to call itself the = name the server's IP will reverse dns lookup to. That is the important check done by those somewhat outdated spam filtering dns checks. I have never thought those dns checks worked effectively for filtering spam, but I = know that some ISPs still try to do filtering using dns checks. The old = school dns checks tried to prevent email address spoofing, but largely failed = to do that. SPF is a solution that actually accomplishes what that old school = dns check filters tried to do. As a function of time, ISPs will drop many = of the outdated dns checks in favor of newer tech like SPF.
The bottom line is that since many ISPs host several domains on a server = and often a single IP address, you cannot be strict about the email = address's domain name vs the hostname of the server. All the dns check can really = do is check to see that the server's hostname matches the hostname shown on = a reverse dns lookup of the server's IP address. For example, an email = server may say it is mail.domain.com. Assuming the server's IP was 1.2.3.4, = then 1.2.3.4 would need to have reverse dns resolving to mail.domain.com in = order to be legit. The email address should be a nonissue as long as the = server's hostname matches its IP's reverse dns lookup. If an additional dns = check does force the server hostname (as given by the email server software) = to match the domain name part of the email address, then there will be = sizeable false positives resulting in countless dropped (but legitimate) emails, because that would basically be mutually exclusive with the first dns = check if the ISP hosted more than one domain per server. Anyway, the way = XMail handles this is fine as long as ISPs are not being stupid about their = dns checks on inbound email. When an ISP does setup something stupid that = ends up blocking email from big hosters, the ISP's customers let them know = about it pretty quickly. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] = On Behalf Of Michael Lugassy Sent: Sunday, September 12, 2004 2:21 PM To: [EMAIL PROTECTED] Subject: [xmail] Re: Problem with multiple instances Davide hi, > Why this? I mean, what the end users really see is the From: header > and not the remote MTA from where the message came from (well, = excluding > Received: headers). Spam filters sometimes compare the FROM: address to the actual mail = server (using reverse DNS and other checks), Moreover, assuming I have 2 competing clients on a single server, this = might look weird to users who do look at the full headers. Am I the only one who require such a feature? Thanks Davide, Michael. - Davide - To unsubscribe from this list: send the line "unsubscribe xmail" in the = body of a message to [EMAIL PROTECTED] For general help: send the line "help" in the body of a message to [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe xmail" in the body of a message to [EMAIL PROTECTED] For general help: send the line "help" in the body of a message to [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe xmail" in the body of a message to [EMAIL PROTECTED] For general help: send the line "help" in the body of a message to [EMAIL PROTECTED]
