I manage many domains and most of them now use third-party outgoing gateways for various reasons. I've been using the "priority" hack to control which domains go through which gateways, but there are only 10 total priorities so I am starting to reach a limit with what I can do.. Here are some ideas for improvement:
1) Allow a "Name" to be given to outgoing gateways. Some of them use the same SMTP server but different account credentials and I have to click them each time to tell them apart. Also the Priority should be displayed on the grid.
2) Allow larger or arbitrary numeric input for priority numbers. E.g. 0-100 or more.
3) Create Outgoing Gateway "Groups". Existing outgoing gateways would be moved to the "Default" group. Then the group could be chosen on a per-domain basis (defaults to Default of course).
4) An alternative to (3): Allow a domain to be configured to use a "Default Outgoing Gateway" which can be chosen from the list of active gateways.
This might not have been a common need before, but with the state of spam filtering being what it is (the difficulty for low-volume IPs to get a good reputation) and the fact that so many great third-party services have popped up in the past several years makes improved support for routing a necessity in my book and the matching up of 10 priorities just doesn't cut it anymore.