I have defined a few custom smtp transports to limit deliveries to certain large domains such as Yahoo and Hotmail. These are applied via the transport map file to match recipient address domains.
There are a large number of recipients I would like to use a custom transport for, but whose actual recipient address domains are all different. The common bond among them is they all use the same MX. These are personal domain names hosted by GoDaddy, so they all use smtp.secureserver.net as the primary MX. Is there a way to apply a custom smtp transport to the MX hostname, rather than the recipient address domain?
