The idea of a relay junkmail with option to enable/disable redirection is excellent!

However, I find the addon and the user experience to be near useless.

BEST UX practice:
1. Click on email field, addon suggests to input relay address.
2. Click on any alias, it gets submitted to field. Nice and easy.

Current flow:
1. Click email field, addons says "You have X aliases left", only "Manage" button available;
2. Click Manage, get redirected to Mozilla sign in page;
3. Sign in to Mozilla;
4. Manually copy alias from the list;
5. Go back to page with email field;
6. Manually paste the alias.