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.