Not quite what you’re asking for, but Fastmail is an email service that offers the multiple addresses thing as a feature out of the box. foo@myname.example.com goes to the same inbox as myname@example.com. Just required a couple of DNS entries.

I’m using purelymail.com with my own domain. It costs peanuts per month (currently at $0.34) and it can forward mail addressed to non-existing mailboxes to a catch-all for any domain you own.

This was my go to method for this exact use-case.

[edit] Privacy wise, I’m not sure what to say, it’s a regular service that offers IMAP/SMTP, so as long as you download all your email and don’t leave it on the server it should be fine. They also mention that for the time that it resides on their server, the data is encrypted.

Essentially any email forwarding services will help you there. You can configure a catch-all.

To me, email is a great protocol where it’s distributed. If you only use any email service as a dumb client, as in don’t rely on their web ui to read email, then it’s very easy to migrate to another platform.

In case of email forwarding, emails are stored at the final destination so it’s even easier to migrate, you just point MX record of your domain to another platform.

1. Privacy Really at the end of day it’s all about who you trust. All service will claim they won’t read your email and obviously they won’t. But let’s say they are working on a spam filtering, they have to monitor it, and at least the operator has to check a field thing such as origin IP, domain, and subject line at least to ensure spam filtering work. So this is a very grey area. If Privacy is about not leaking the original emails are almost all email forwarding services are good here

2. Cost When we acquire a domain, we pay about $10-20 depend on provider or domian type, so I generally assume cost about $12 for email forwarding is good here.

3. Reliability/Longevity of the service In my experience, icloud/hotmail has kind of dumb/sensitive spam filtering sometime may flagged your legitimates email as spam. Esepcially if you used to receive email from someone directly at your domain, or your real inbox is new.

Many provider are support ARC now so we will have better delivery(because SPF will fail when forwarding email) and ARC is a must.

4. Features Some services offer webhook(so you can example, fire a webhook to process your receipt emails- this is what I do and essentially build an API for my bank on top of google sheet api :-) will open source it soon too. Some offer regex routing and URL redirection too. Some offer maillog so you an look into the mailqueue to know if an email is flagged as spam or never come to your final inbox

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FULL DISCLOUSE: I run an hanami, an email forwarding service

Migadu lets you create virtually emails and addresses for a given domain (I say “virtually” unlimited because they claim there isn’t a limit, but they might change that if abuse occurs).

You do have to pay for Migadu email, but this is a really nice bonus.

Additionally, almost all email providers let you add a “+” to your email address: username+website@domain.tld is an automatic alias for username@domain.tld.

All three are open source and probably can be self hosted. Not sure if the common email pitfalls apply and how much work it would be to set them up. Maybe someone is doing that and can/cannot recommend it?

I recently came across this which looks good to me for your use case especially as Privacy is one of the features you have listed:

https://posteo.de/en

For one-shot redirections, I’m using https://jetable.org/

edit – Just found the source code: https://github.com/yverry/jetable

There’s pobox.com from Fastmail

What about your own domain with a catch all?

It’s what I’m doing, for years. Works perfectly!

I’m using mailbox.org:

• Privacy: good (e.g. you can encrypt all incoming mails with a GPG key)
• Cost: 1 EUR/month
• Reliability/Longevity of the service: I had maybe 1-2 hours outage in the last 2 years or so
• Features: several, but I don’t use them

If you don’t have a domain you can still generate random aliases (@temp.mailbox.org). However, these random aliases will be deleted after a month. So it’s probably not the behavior you want.

(Btw. friend invitations include 3 months for free. Drop me a PM if you need one).

I run an opensource service that forward but requires you to use your own domain (s).

https://mx.ax https://github.com/jawr/mxax

There is a free tier and currently the paid tier is a very reasonable $3. Of course this is based on fair usage.

You can define the level of logging you want, some users might want to be able to check for bounced emails, whereas some want no logging at all.

I want to invest some more time in to this project, but am a little busy elsewhere, but I do use it for all my own domains/emails!

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Assuming I’m following your needs correctly, I would recommend https://forwardemail.net. It has a free tier for easy testing. The paid tier is needed to hide the redirect target address, along with other extra features. I’ve been using it for several years, and it works quite well!