They're not literally unlimited, but the limit is high enough that in practice, you can have a separate email address for every service that you use.
I do have my own domain, but I don't typically use it for most 3rd-party services. The reason I like aliases more is because if I use the gmail trick or my own domain, there's still a unique piece of information that's tied to my name. In other words, it's still identifying.
Most spammers know to strip the pluses from gmail accounts, so you're not really doing anything at all by adding those. And even if a spammer can't guess your other email addresses, they still know who you are. I'm not particularly secretive about my identity online -- I use my real name as my handle. So it's not even always about blocking spam -- sometimes you want to use an email without giving a company a very obvious link to who you are.
e.g. [email protected], [email protected], etc.
I did this for years before switching to a custom domain and it worked very well for me.
I think of throwaway addresses the same way as I think of a VPN. I shouldn't be the only person on the domain I'm using, and there shouldn't be any persistent information in the address.
With Fastmail, the only information I have to give up is that it is a Fastmail account. I can have `<some_random_string>@fastmail.com`, which makes it much harder for an advertiser or spammer to link my identity from that email to another one.
Is that possible with Fastmail without having your own domain? I've been looking for a mail provider where you can create unlimited mail addresses to prevent me from being tracked across services for some time now. The problem with using your own domain ([email protected] [email protected] etc) is that only laziness of not implementing automatic domain matching is keeping my identities separate.
If anybody knows of a mail provider who provides that (even with random mailbox names like [email protected]) I would be grateful if you could let me know.