I'm old. The title word "bulletproof" has some strong negative connotations for me. Are you aware of the links between that word and people providing unsolicited bulk email? Is that link still strong, or am I being oversensitive? (I'm aware you're using it in a different context; "bulletproof" here meaning "will work in many different email clients".)
The site looks nice, so good luck!
This did cross my mind, but I think (I'm not 100% sure) that bulletproof is a highly specialize word. You'd only make this connection if you we're interested in bulletproof hosting. You're the first one to mention it so I think you might just be oversensitive :) It would be interesting to see if lots of other people make this connection.
I must have written 30 different tag lines for the homepage, so I might try split-testing them at some point.
P.S. The homepage tag-line was almost... "Rich HTML email development that isn't like punching yourself in the face."
Always great to see new tools in the email space - would love to get an invite to check out the system and potential integrations.
Your invite should come straight through :)