Very good feature, as usual by Firefox team.
Only missing the ability to delete relays to create new ones.

lacking documentation to fully explain it.
far too confusing to understand how it works.
EDIT: DOES NOT EVEN WORK AT ALL.
SKIP THIS GARBAGE 'FEATURE'!

only 5 alias 📨 please add more 💌📧✉📮📫📪📬📭

It's quite a convenient addition to the mozilla ecosystem. Saves me from signing up for a dodgy or pricey alternative.

i love this, i suggest a rapid button for insert an existent alias, not only generate

Interfering with some normal logins where an e-mail has already been registered.

Great idea! I haven't actually tried it yet and I'm going to disable it. It's very frequently interfering with the usual "remembered" email addresses/passwords on websites. Specifically, visit a site, email address and password are filled in, click "login" or equivalent, site responds with "enter a valid email address". Sometimes I cannot get past that - I have found a workaround by accident - click twice. So until this add-on matures, I'll leave on the back burner . . .

The service is excellent. It just works and I can't discern any meaningful lag due to having my email forwarded so great job, Mozilla! However, in regards to this add-on specifically, I have a major complaint: I believe if you're going to have an auto-fill feature that places a glyph button in email fields, then the add-on should act like a password vault and let you click on the button > select the created alias you want > address is filled in the field. The add-on has half of that paradigm done well. It allows creation of new aliases and the option to take you into the "full" add-on management screen for more detailed changes. However, it's rather annoying to use a password vault that auto-fills but then when signing up with a relay address (i.e. my vault has nothing to remember yet to auto-fill), I have to go to manage my aliases and copy + paste them into the field. Again, though, I really value the service and it would be a 5-star extension if it let me pick and fill the alias within the current page's form.