I am a developer, and have a home lab. On it, I have a fully functional exchange server, and I would like to build apps where I can test its integration.

A long story short, I am unable to send or receive emails to the outside world as I am a Comcast Residential customer, and that's okay.

However, I would like to know if there is a way to proxy my inbound/outbound emails. I also have a virtual machine on Azure so if there is a specific redirection of traffic that I can make to and from that, it would be useful.

Another option that I thought of, and I don't know that its even possible, is this, is there a way to get a static IP from another service, and still be able to use it with my current provider?

Lastly, if I use Azure in the cloud with a VPN connection into my network, can I force my inbound/outbound traffic through that, to use its external IP address for mail?

Please help me describe any (or multiple) scenarios as listed above. This is very helpful.

PS: Please be nice, I am a rising infrastructure geek :), but a hard core developer!

  • Take a look here, this should give you an idea. serverfault.com/questions/639289/… that it up and running it would a case of making sure your exchange server uses this server as a smart host, but that your firewall routes traffic along the VPN – Drifter104 Nov 30 '15 at 14:26
  • That links to my own question. – Bill Daugherty Nov 30 '15 at 14:27
  • fixed the link, sorry about that – Drifter104 Nov 30 '15 at 14:29

Seeing as I do this now, it's very easy to accomplish.

Basically, you setup a hosted anti-spam server that is also your smart host, I used a very VERY cheap VPS to do this as cpu/memory isn't an issue with email ($3.50/month).

The trick is to send/receive all email on non-standard ports to the VPS, I used Centos7 and Postfix (I added postgrey, spf, dkim, and your top RBLs too)

(Smart Host) |ExcahngeServer >> postfix:2525 >> Internet

(Spam Filter)|Internet >> Postfix >> ExchangeServer:2525

Since I also have a dynamic IP, I could use sasl_auth to do authenticated relay on port 587, however I run all my internal systems on a static IPv6 network via HE.net's tunnel broker.

*Note I would use a VPS with IPv4 and IPv6 connectivity, and configure FCrDNS for both.

  • VPS = Virtual Private Server? I know it may be against the rules, but what provider do you suggest, is Azure okay for this? Also, how do I get my hands on PostFix? – Bill Daugherty Nov 30 '15 at 16:31
  • Postfix is a standard linux package, you could also use any cloud spam filter and a relay host. I used buyvm.net – Jacob Evans Nov 30 '15 at 16:39
  • Is there something equivalent to Postfix but for Windows? – Bill Daugherty Nov 30 '15 at 17:16
  • Exchange edge server – Jacob Evans Nov 30 '15 at 17:18
  • @BillDaugherty Have a look at the Standard/free version of mailenable.com – TessellatingHeckler Nov 30 '15 at 18:08

The usual way to deal with this is to simply have your email use one of the many off site services for spam filtering. They can usually do both inbound and outbound email for you. For outbound email you would configure a smart host within Exchange.

Another method is to use a "mail hop" service. Again this will do similar to the above, but send email to your server via an alternative port. A lot of those services will provide an outbound service as well. The major drawback with that is the most effective spam filtering is done before delivery, so a pure mail hop service would stop that from happening, leaving you with dealing with spam as it is delivered to you. That means no recipient filtering and unable to use blacklists (if that is your choice of tool).

However, as you have an Azure account, what I would do is use that service to provide the connection. Setup the account with a static IP address, then spin up the free Kemp Load Balancer. It can then be configured to send email to an alternative port on your network. Still has the same problem as the mail hop, but is under your control. For outbound email, use your ISPs SMTP server as a smart host.

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