Mozilla are introducing a new thing to their accounts (presumably). Essentially a plugin you can click to get a new alias email address that will forward to your real email.
It’s in an invite only beta at the moment. They say they’ll have an invite page up soon.
Been using Spamgourmet for the same purpose for years. The website is uh… not very up to date, but it works fine.
Im going to pester my local firefox community, see if I can get a beta access. You guys should probably try to find/search them on Telegram if you are interested.
I unfortunately have no Firefox contacts 
It looks like spamgourmet is designed for one-off form submissions and the like. The limit on messages received per address would make it unhelpful for things like account signups, where later on you might want to reset a forgotten password.
I used to use Mailinator, back when they still had obfuscated mailbox forwarding/aliases (m8r-<something>). If you picked a 12+ character long mailbox name to start with, no one could guess it, and you could just give out the obfuscated address to sites. This way even if your account email was listed somewhere it would still be useless to someone trying to take over your account, since they would not be able to view the inbox on Mailinator.
I think this should just be built-in to all email services; Apple is part way there, but it seems as though it is limited to their single-sign-on system only, which has other issues (I think it might disclose your AppleID name to the service you sign up for).
In my opinion, everything even partially automated, be it account signup, help desk, or especially marketing, should always get an obfuscated or randomised address. Only a real human being directly using a Mail User Agent (IMAP/POP/webmail client) should ever have access to a human-readable address. Even then, I think it might make sense to split family, friends, neighbours, into separate addresses/aliases.
On that note, it is ironic to see Mozilla’s Private Relay service coming about only after Thunderbird has partially left the fold. They are still somewhat connected to Mozilla, so maybe we might see an “integration” of some sort.
Yes, it is designed for that. But you can add trusted senders per address that ignore the mail limit.
It sounds like this will be a similar tech as Apples aliased emails used for sign up, perhaps with Mozillas option being a bit more flexible in use.
What about aliases inside your existing mail account?
You can create additional aliases in i.e. Outlook.com and hand those to different sites you register to.
Am i understanding this right, the Firefox Realy is the same, but with an additional addon, that automates the stuff?
I think another benefit is the east of generating them and destroying them, they aren’t associated directly with your email account either.
But yeah, they essentially automate the part of generating the email when needed, and provide and interface to remove then or delete them when needed.
Nope the boss of the local official firefox community sadly has no beta to lend. 
This is now available as a beta
(Your might need an invite, I got an email about it)
New spam dump … Sweet