I am working on designing an email integration from Salesforce that will use Sendgrid with click/open tracking, for our consulting customer. I want to ensure that on an ongoing basis we can set up this integration in development environments and test the round-trip of sending emails and having the statistics come back by webhook. I was thinking maybe subusers would be the way to do this, one subuser per sandbox or production environment. So I wanted to ask the following, since I don't currently have Pro to test this with (it will be a little while before we can get the customer authorization to set up billing on a paid account) :
Can one authenticated domain be used by multiple subusers? (i.e. we want any of the sandboxes to be able to send as mycustomer.com email addresses for testing purposes)
Can each subuser have a different webhook configuration? (i.e. subuser 1 pushes events to SF sandbox 1, subuser 2 pushes events to SF sandbox 2, primary user pushes events to SF production)
You can assign an authenticated domain to a subuser.
I can't find the documentation for it right now, but each subuser has their own event webhook.