This feature, offered by many browsers and operating systems, is a great way to obscure your "real" email address, to help cut down on Spam.
The issue with using this feature for a Forum registration is eventually that hidden email will expire, or it's such a jumbled-up random email, you won't be able to use it to recover your account when you forget the randomly-generated password that same software came up with.
In summary, when you register here, you should use your real email address, not a randomly-generated one, and record the password you use.
That way, "when" you forget your password (and you know who you are), you can recover your account using your real email address, and not something created, and then forgotten, several months ago.
The issue with using this feature for a Forum registration is eventually that hidden email will expire, or it's such a jumbled-up random email, you won't be able to use it to recover your account when you forget the randomly-generated password that same software came up with.
In summary, when you register here, you should use your real email address, not a randomly-generated one, and record the password you use.
That way, "when" you forget your password (and you know who you are), you can recover your account using your real email address, and not something created, and then forgotten, several months ago.