iCloud is almost justified by the number of expendable email addresses one can allocate

It's incredible how much information some people express through their email address. Patterns like:

"[firstname].[lastname].[year of birth]@gmail.com"

are still surprisingly common and indicate race, gender and age. These persistent addresses can also be cross referenced to various leaked datasets to get everything from phone numbers to dietary habits.

I use SimpleLogin aliases via my Proton subscription. But I'm terrified of what happens if I lose access to my Proton account, either because I get banned or the company disappears into a black hole. It would be a personal disaster to lose access to hundreds of accounts.

I could buy my own domains and have them forward to Proton but then they aren't disposable, unless I were to buy a domain for literally every account.

I've been using Fastmail the past few years and I'm a great fan. Not alone does it allow me to generate up to 600 random email addresses using domains owned by Fastmail, it also supports catch-all email addresses using my own domains. Ever since I switched to Fastmail I've been able to use a unique email address for each online service that I sign up for.

Does anyone have a good self-hosted tool for doing this?

If you run Postfix yourself, here's something I wrote to scratch that itch: https://github.com/m3047/trualias

I have a catchall rule on my personal domain, so I can trivially make up a new <recipientname@mydomain.com> for everyone who wants an email address. If I get more than a small amount of mail from some sender, I just set up a forwarding rule which deposits everything received on that address into an IMAP folder called "recipientname". If the address becomes compromised - which has happened rather less often than I expected it might, when I began using this scheme - I just change the rule and route the mail to /dev/null instead.

The problem with giving a throwaway e-mail address to people you may have a conversation with is that you have the additional hassle of having to use that address as your Sender identity when you subsequently reply to their e-mails.

Say they write you first. They use your throwaway address. If you just reply to that, you are now using your main address; you have to get your e-mail program to switch to the alternative identity, consistent with the e-mail thread.

That's just one more moving part in the scheme requiring configuration. Some mail programs keep sending identities in their own database. You have to create the entry there and then explicitly switch to it when composing an e-mail.

To automate that, the throwaway e-mail address system now has to configure your client database in addition to the mail-server-side stuff. Plus your e-mail program has to be patched to select that sender based on an address appearing in the To: or Cc: list of the item you are replying to.

Email address secret is uniquely silly as the entire point of the address is to receive mail.

Capitalism will ensure spam survives.

The end result of these two facts is that good filtering and staying zen about a few slipping by is the secret to email happiness.