Although the extension could use some work, EXCELLENT service, and useful enough for protecting my privacy that I have enrolled in their premium $0.99/mo. plan.
Prior to this I was using mailinator whenever I wanted a single-use address, and while that's great if the account is a "throwaway", some accounts I actually intend to maintain. For non-throwaway accounts, there are several reasons mailinator is not a good choice, most notable of which: ANYONE can access a mailinator inbox.
After enrolling in Relay's premium plan, I have gradually started migrating my accounts to relay aliases, and so far I'm loving it. For example:
1. Each account having a different alias allows me to tell what account it pertains to just from the subject line.
2. In the event a company shares my email alias with another, I can trace that too!
3. By reducing the number of emails that go "directly" to my real email address, it becomes easier to filter out junk from accounts or interactions I've long since abandoned or never initiated the first place.
Now, as I said, the extension itself could use some work:
1. Sometimes, even if the option is checked to show the extension's icon on email fields, it will not show. When this happens, the only workaround is to visit Mozilla Relay's subsite at relay.Mozilla.org. I can't manage or grab my aliases via the toolbar button, for some reason
2. With some sites, like Nintendolife, the extension icon will show, but will only let you search for existing aliases, rather than offering to create a new alias for the registration. Perhaps this is another tool that should be available in the toolbar button?
3. See also: review by "Firefox user 13593578", which was posted 24 days prior to this one.

nice

Il faudrait pouvoir désactiver l'extension sur certains domaines.

It works well, but I don't understand why I can't generate a "mask" email using it? Seeing as this is one of the features of having a paid account, the fact I still have to go to the website to generate one is quite jarring and annoying. But otherwise, this addon works very well, thank you.

Does what I need. About the only thing that could be better is dismissing the help text when I click the toolbar button.

It's useful, but I could use a simpler means to get the mail address - it would be nice to have copy button upon clicking the icon - 2 clicks to have the address, instead of going to "Manage all masks" wait for it to load, sign in (I have no idea why it sing off) and then get it.

Great add-on, just wish there was a way to remove it from the right click menu.

Bonne interface, bonne intégration, très pratique.
Nota pour debug (v2.4.5) : lorsque le module est activé, il m'est impossible de me connecter au site tgvinoui.sncf (avec une vraie adresse), car la page est systématiquement rechargée automatiquement dès que je saisie l'e-mail.

Most useful features are paid.