You effectively have unlimited (not infinite) e-mail addresses with Gmail and many other e-mail providers by using the + sign. E.g. fibers+HN@gmail.com
I am well aware of that feature gmail has and have abused it in the past with many websites, but the parent said that some SaaS platforms block gmail altogether. It seems like a shoddy fix if you can get a really cheap domain and essentially do the same to register accounts.
Yeah, its like putting extra locks on the front door while the back door is wide open. However, most people would try the front door first.
A lot of domains have that feature btw. Gmail's specific feature is with the dots functioning as catch-all [1] (though Facebook apparently has the very same feature).
Except sites that mistakenly disallowed the + symbol.
Also, it's very easy to mechanically identify all such users because of the + symbol, which, if you are trying to prevent your real email address from revealed means it's not that useful...
Regarding the former, my ISP allows me to set forwarding email address. I could temporarily use these until X date or until they receive (a lot of) spam. Though all spam gets filtered anyway.
Regarding the latter, when they email you directly without the + you can be very strict. You could even apply whitelisting.
Actually I do. I bought a domain of my shortened initials and this domain catches all the emails sent to it. Every entity gets a custom address: bank@my-in.com, ikea@..., Etc.
I use Fastmail's subdomain addressing [1] to sign up for services in a very similar manner. I'm certainly sympathetic to bad services abusing the privilege of having your email address. My contention is that while this is the purported benefit of mailinator.com, in reality many people use it to abuse services.
In other words, there's a big difference between using ikea@ and saastrial1@, saastrial2@, saastrial3@,.. and so on to keep signing up for trials with the same SaaS provider.