Well there are a few reasons the main one being that I'm afraid that having the firewall also act as the mail server that everyone in the office is hitting every 3-5 minutes might put a strain on the box that I currently have allocated to the duty of firewall.
Also, I'm already hosting email for a small virtual domain on the firewall and I'm not clear on how to handle same names in different domains (i.e. joe@primary.com and joe@virtual.net.
So you're saying that using the Delegate option would allow the email for the delgated domain to pass through virus checking and spam labeling prior to being passed along to the corp. server? If so, that's spectacular but how will I know for sure that it's happening? Maybe I could email the EICAR test through it or something?
