Hi Anthony. I wanted to chime in because I just set up Domain Forwarding in Smartermail for one of our customers this morning. Domain Forwarding and Backup MX are two different things. For example... If you have a primary server and you want to use the Smartermail server as an antispam gateway for the primary server, you can set up Domain Forwarding in Smartermail for your primary mail server. What you would do is add an Incoming Gateway. For the Gateway Mode option, you would choose Domain Forward. Then you would add the IP of your primary server. You can put a check in Disable Graylisting if you like. If your primary server is also a Smartermail server, you would need to put a check in the "Enable Smartermail Gateway Mode" box and choose whether or not you want to use User Verification. If you do, pop down the User Verification box and choose "Web Service". Once you do that, click the Smartermail Gateway tab and enter your URL and admin information for your Smartermail Admin interface. Next, click the Domains tab and enter the domain names that you want the server to accept mail for. Whatever domains you specify, be sure to point the MX records to the Smartermail server so all mail for those domains will be sent to it for spam scanning. Once Smartermail scans it, it will be delivered to whatever recipients it was addressed to. If your primary server is not a Smartermail server, you can skip the steps that I mentioned about in reference to Smartermail Gateway mode.
So to summarize, Domain Forwarding is used when you want to use the Smartermail server as an anti-spam gateway for your primary server.
Now, Backup MX is different. This is used as a Store and Forward type feature for your primary mail server in case it ever goes down. If it goes down, mail will be sent to your Smartermail server and held there until your primary server becomes available again. As far as I know, you cannot set this up for a per-domain configuration within Smartermail. However, there is a work-around. If you set up Backup MX and your primary server goes down, all mail sent to the primary server will instead be redirected to the Smartermail server and held there until your primary server is back up. In order to make this work, you would have to add secondary MX records to your zones in your DNS for mail which point to the Smartermail server. So basically, when someone sends mail to someone on your primary server, and it's down, it will send to the secondary MX, which is your Smartermail server and the Smartemail server will hold the mail.
Now, about the workaround... If you wanted to set up a Backup MX, but you didn't want it to catch mail from certain domains if your primary server goes down, all you need to do is NOT add the secondary MX record to your DNS zones for those domains. I'm not sure why you would want to omit domains from the BackupMX, but if you do, that is how you would do it. Just be aware that if you omit domains from the Backup MX and your primary server goes down, all mail to those particular domains will be bounced back to the senders.
I hope this helps. Take care!
Linda Pagillo
Mail's Best Friend
Email: linda.pagillo@mailsbestfriend.com
Web: www.mailsbestfriend.com
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