It's important for our emails to render without issues across all supported email clients and devices: Outlook, Yahoo, Comcast, Gmail, iPhone, Android, tablets, etc.
The only word I can think of is "bulletproof" ("bulletproof email", "bulletproof email components") but I'm not sure if that's the correct technical term:
We have a focus on developing ("bulletproof") emails- our emails render on any device or email client.
Is there a widely-used term to describe an email that renders well across all clients and devices?