I just did something for SMF:
http://www.simplemachines.org/community/index.php?topic=512386.msg3620606#msg3620606
it should be mostly the same for Elk.
Do we have any way to hook the mailing system?
I'm not sure we have a hook in the mail system, I don't think we do but O:-)
So does this basically offload your server or host and post mail to EM and then it gets sent? Sounds cool but probably addon material (with any hooks needed added to core) ...
I use AWS SES so this was an interesting title, but there is a SMTP relay and looking at Elastic Email, they also have an SMTP relay. So, it seems that you can just use those instead of using a HTTP GET, right?