Exchange 2010 multiple accepted domains and cloud spam filtering

Ok I have an interesting issue that our spam provider (Barracuda) doesn't seem to have an answer to. We have Exchange 2010 and need to have a couple other domains (humanitarian project of one of our founders and a couple domains from a company we acquired) onto our server. Easy enough to do as multiple accepted domains.

Now the tricky part is, we use Barracuda cloud spam filtering. When you add a domain to their portal, you get specific hostnames for inbound/outbound spam filtering. This causes a problem on my end. How can I send each of these separate domains from our Exchange server to these specific smarthosts? I can't seem to find how/if Exchange can do this natively, and 3rd party add-ons isn't an option right now.

Thanks!

*** Edit for answer/more detailed issue explaination ***

Thanks everyone for the responses. It seems I was worried about nothing. After speaking to another tech, they confirmed that the assigned hostnames are "recommended". Barracuda will actually accept inbound mail from your ip address to any of its inbound smarthosts.

Now still for my own curiosity, I want to figure out of this is still actually possible

So just to give better detail, here is what I was trying to accomplish:

We have our primary AD domain. Lets call this domain1.com. This is what our default domain for Exchange is also (internal is .int, external .com). We have two external domains would have added as Accepted Domains in Exchange. Lets call these domain2.com and domain3.com.

We use Barracuda Cloud Services as our spam filtering provider. When I access the portal and add these two domains, they are assigned their own unique barracuda inbound/outbound smarthosts, as seen below:

domain1.com -> smarthost1.barracuda.com
domain2.com -> smarthost2.barracuda.com
domain3.com -> smarthost3.barracuda.com

In Exchange, I configured a send connector that routes all of our outbound email to smarthost1.barracuda.com. What I would like to try and accomplish, is this:

If a user sends an email from internal -> external using their user@domain2.com account, I would like that email to be sent to smarthost2.barracuda.com. Same if they send from user@domain3.com, I would like that email to be sent to smarthost3.barracuda.com. I can't seem to find this as a native ability with Exchange 2010. I have found reference to 3rd party tools and add-ons, which we would like to avoid if possible.

Does anyone have any thoughts on how this can be done?

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it_consultant

I think this is possible by doing a custom send connector and a custom address space for that connector - which would require you to use a smarthost for the connector. You would need a separate connector for each domain you send from.

Create an SMTP Send Connector: Exchange 2010 Help

crrussell3

Correct me if I am wrong, but aren't send connectors scoped for the domain(s) that you are sending to, not sending from? So if I put say *.contoso.com, all emails addressed to contoso.com will use said send connector. It won't matter which of my domains I am sending from, domain1, 2 or 3.

gbdavidx

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it_consultant

crrussell3 wrote: »

Correct me if I am wrong, but aren't send connectors scoped for the domain(s) that you are sending to, not sending from? So if I put say *.contoso.com, all emails addressed to contoso.com will use said send connector. It won't matter which of my domains I am sending from, domain1, 2 or 3.

I think you are right, dang I knew it wouldn't be so easy! Otherwise you need to set up new domains in your forest so your HT servers can have their own special send connectors and organize your mailboxes accordingly. We send from multiple domains as well but we have onsite filters so it is much easier for us.

TheProf

Maybe I misunderstood the question, but you're trying to send out emails out of your Exchange server from a particular domain, for example contoso.com and for it to automatically associate it self with the hostname in the barracuda cloud?

Edit: Send connectors, are used to route mail either between exchange organizations or to smarthosts/gateways outside. So, you'd need a send connector to send email out, meaning you probably already have one defined in your exchange organization for the barracuda spam filter if that's what you use as your smarthost. You can also have different types of send connectors defined such as the connectors that are used to route email between specific domains such as you mention above.

crrussell3

Thanks everyone for the responses. It seems I was worried about nothing. After speaking to another tech, they confirmed that the assigned hostnames are "recommended". Barracuda will actually accept inbound mail from your ip address to any of its inbound smarthosts.

Now still for my own curiosity, I want to figure out of this is still actually possible

it_consultant

You would have to create completely separate internal domains with Exchange servers (which would have their own send connector) and you would have to segregate your email accounts according to the domain you want to send from. As far as I can tell, Exchange is not designed with the capability to sniff outbound email and modify the next hop of the message. If this capability DID exist then I suspect it would actually be under transport rules. Transport rules gives us limited abilities to modify emails that are flowing in and out of the server.

We handle this from our in house spam filter. The ability to modify outbound mail (including relaying them to different servers based on the envelope sender) is much more in depth.

crrussell3

Thanks it_consultant. That seems to be everything I am researching too. Oh well, would have been nice.