Posteo is in fact open source.

Most “privacy” webmail providers, such as ProtonMail, Tutanota, and mainstream services like Gmail, Yahoo Mail, Outlook, and AOL Mail, are labeled as proprietary because they use closed-source software, meaning the code isn’t publicly available for review. These services operate on controlled servers, with features and infrastructures managed entirely by the company. The proprietary nature allows them to implement unique features and monetization strategies, but it also requires users to trust the company’s privacy and security practices without independent verification. This contrasts with open-source alternatives where users can inspect and verify the code themselves.

It is very difficult to run an email provider and not get banned by the others. Google, Microsoft, and Apple control the US market, for example. If they decide your domain is spam, you suddenly can’t email anyone with a Gmail or Hotmail or Apple account. Avoiding getting banned means you have to regulate your own outgoing emails very carefully, rate-limit them just right, and yet also build up a reputation of trustworthiness by sending a lot of emails that don’t get marked as spam.

The only privacy-secure way to do your email would be DIY but this risks getting banned like… all the time.

Personally, I recommend having your own domain and setting up MX records to a reliable email provider that is not one of the big ones and ideally offers some kind of theoretical inbox protection (please note that they could always still read everything if they just copied all incoming messages to another database as well).

Email is itself not very secure. You can use GPG to make it better but most people won’t know how to receive your messages or send secure ones. For security, I recommend using a dedicated e2e chat service or in-person communication.

I use Proton but tbh I don’t really know if there is a more privacy focused one.

@Charger8232 Lists from #Alternativeto (which this is based on) are usually not very reliable and show information that just isn’t correct on a service or often includes services that are not real Alternatives to what you were looking for in the first place. The only thing that helps against that is doing your own research.

To pick out one example (I don’t have time to them all): they list #Posteo as being proprietary which just isn’t correct. That company is as #opensource as they come.

@Charger8232 @g0nz4 I guess in that case “proprietary” refers to the owners of the platform itself but not to the code of software. But then, they should make the distinction between proprietary/communitary and open source/proprietary code. Even between free/paid services. So, IMO that list from alternativeto is confusing.

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• Skiff = Notion now, I doubt that it will be open source, but happy to see source code.
• Lavabit open source ? Where’s the code ?
• Roundcube is webmail software, not a webmail provider.
• Mailpile is email software for desktops, not a webmail provider.

@Charger8232 Yes.