Solved: Adding a second interface for message delivery

richardacarey · ‎12-29-2009

Hello,

Currently I have a C350 configured with one interface which handles all inbound and outbound mail. I've been informed that there will be a marketing initiative where emails will be sent out from one of our web servers. I'd like to add the second interface and set up a rule to deliver those email from that interface as opposed to the primary.

Here is what I plan to do:

Assign it an address on a separate subnet
give it a public address and A record
set up an outbound content filter that will deliver mail out of that interface if it matches the rule

My thinking is that if there are issues with the way the marketing emails are sent (i.e. they generate complaints from recipients), then the IP address of the second interface would get the poor reputation score as opposed to the primary interface.

Is there a step I am missing? Is the overall strategy valid?

Any insight would be greatly appreciated. Thanks.

steven_geerts · ‎12-30-2009

Hello Richard,

After a quick review I think you missed the creation of a reversed DNS record (PTR record) for the new IP address. For SMTP traffic it's really important to have a good PTR record.

Besides that I would invite you to read carefully the topics about "virtual gateways" in you online documentation. Those are a specially created solution for your problem and if I remember right you can even use a secondary IP address on you existing interface for it.

Good luck!

PS: kudos for your marketing department, most of the times those guys start their e-mail cannons without even thinking about any possible side effect on the main production mail flow. :-)

Steven

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steven_geerts · ‎12-30-2009

Hello Richard,

After a quick review I think you missed the creation of a reversed DNS record (PTR record) for the new IP address. For SMTP traffic it's really important to have a good PTR record.

Besides that I would invite you to read carefully the topics about "virtual gateways" in you online documentation. Those are a specially created solution for your problem and if I remember right you can even use a secondary IP address on you existing interface for it.

Good luck!

PS: kudos for your marketing department, most of the times those guys start their e-mail cannons without even thinking about any possible side effect on the main production mail flow. :-)

Steven

richardacarey · ‎12-31-2009

I think that's the answer I'm looking for. It's definately easier configuring the virtual gateway on the same physical interface so I'll go that route and use the altsrchost command to map to the virtual gateway.

Thanks!

Donald Nash · ‎01-03-2010

Just be careful assigning a second address to an existing interface. I found out the hard way that the address chosen as "primary" is determined by the order in which the addresses sort lexicographically. So if the same interface has two different addresses "W.X.Y.7" and "W.X.Y.17", then the .17 address will be the primary address. When I did this, suddenly all my mail started being sent via the new address I just added, which I had intended to be a virtual gateway address. I got it corrected easily enough with a message filter, but it's something to keep in mind.