Re: [nznog] Continued problems with xtra email

On 9/3/07, Joe Abley wrote:

On 2-Sep-2007, at 1822, Bojan Zdrnja wrote:

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On 9/3/07, Joe Abley wrote:

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On 2-Sep-2007, at 1546, Bojan Zdrnja wrote:

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Please tell us that both [A] and [B] know all your users and domains (in other words: they reject e-mails for non existent users during the SMTP session).

[A] and [B] are networks, not mail servers.

Networks? So what do they have to do with MX records and multiple servers then?

If you read the message you replied to and take note of what was actually written, as well as what you assumed was written, all will be revealed.

You still didn't answer then my original question. Let me paste that again to remind you (and what you said): In the original post you said:

Suppose some device at [C] tries to send me mail, and at the time it chooses to attempt delivery, there's a network problem which prevents traffic from getting through. It instead delivers to the backup MX at [B]. There is no network problem between [B] and [A], so mail is forwarded on straight away.

So there is an MTA in both networks [A] and [B]. Then I said:

Please tell us that both [A] and [B] know all your users and domains (in other words: they reject e-mails for non existent users during the SMTP session).

And you said:

[A] and [B] are networks, not mail servers.

Sure, they are networks, but they both have MTAs. If your MTA in network [A] is your primary (and let's hope it's properly configured to reject e-mails for non existent users immediately) and the one in [B] has no idea about your users but knows that it has to accept everything for [A]'s domain then you have a problem I mentioned before. The benefit of having [B] as you described it is *only* if the network between [A] and [B] is private (otherwise it should be routable so [C] should be able to get to [A] over [B]). If this is the case, you can still have both of them as 1 MX record so you try to split the load between them. As I said, if MTA in [B] is secondary, you'll almost certainly see *higher* spam load on it than on [A]. Bojan