Before getting started with EzIsland's Email service, make sure you have read the disclaimer and have signed up for an EzIsland account.
Email was one of the first protocols developed for the internet. Since it is so old, the protocol has been updated many times to keep up with modern expectations. As a result, running an email server is a very complex task oftentimes reserved for big tech companies, an employee's buisness, internet service providers, and college/university institutions. In general, any emails sent through these providers can be read and stored by them. One common practice is to flag certain keywords in emails which might require further attention. I remember distinctly that my college used that tactic to determine when students would plan rallies or protests. In one case, an email about a small tabling event was mistakenly flagged by their algorithm and the police showed up only to find two students handing out flyers!
While using EzIsland can help keep your emails secure, emails sent outside of EzIsland's network will still be stored and read by the receiver's email provider. Since you'll probably want to send and receive email to and from other email providers, the best solution is to use end-to-end encryption. Unfortunately, the process of encrypting emails is quite complex and not easily facilitated by most email software. Below, I will explain how Email encryption works, and which Email clients you can use for connecting to EzIsland.
The most common form of email encryption is called PGP. PGP (pretty good privacy) is an open standard for managing encryption for uses well beyond email. To talk to someone using encrypted emails, both you and the email recipient need to generate PGP keys for every device that connects to the email provider. You will also need a way to send your public PGP keys to the person you want to communicate. This can be done through a separate secure channel such as an encrypted EzIsland chat message. Some email clients automate this process for you by allowing you to send these PGP keys through email itself. To send an email to your recipient, you first encrypt that email using each of the public PGP keys that your recipient sent you. The recipient can then use their own private PGP keys to decrypt it. The following section suggests various email clients and offers links for instructions on how to set up your PGP keys, send your keys to the recipient, and encrypt your emails with these keys.
I have listed the best email clients available for each platform below along with instructions for how to install them. All these clients are open source and free to use. When using these clients, they may prompt you for information about the EzIsland email server. Filling in this information correctly is crucial to getting the client to connect and send emails. In paricular, the client will ask for your email address and password. Your email address is your EzIsland username followed by @ezisland.org and your password will be your EzIsland password.
The client may also ask for information about the SMTP relay and the IMAP server. The SMTP relay is used to transmit and receive your emails to and from the internet while the IMAP server is used to download your emails from the EzIsland server. For EzIsland, the SMTP server runs on port 587 using the STARTTLS protocol (sometimes called submission) at mail.ezisland.org. If asked for the SMTP password type, you should tell the client that the relay uses "normal" or "cleartext" passwords.
If asked about the IMAP server, you should tell the client that the IMAP server uses port 993 with the SSL/TLS protocol at imap.ezisland.org. Additionally, if asked for the IMAP password type, you should tell the client that EzIsland uses "normal" or "cleartext" passwords.
Finally, if the client asks about a POP or POP3 server, you should just ignore it. POP/POP3 is an old protocol that has since been replaced by IMAP, and EzIsland does not run POP/POP3 at all.
Thunderbird is currently the best open source email client for windows, linux and MacOS. It can be installed through their website, through the Mac App store, or through a linux distributions repository. PGP encryption through Thunderbird requires a plugin called Enigmail. Information about how to set up and use this plugin can be found on Thunderbird's PGP encryption page.
The best open source email client for Android is K-9 Mail. It can be installed through their webiste, the Google Play store, or through F-Droid, an Android package manager for free and open source software. PGP encryption requires the OpenKeychain app as well. Instructions for setting up PGP encryption using this app are available on K-9 Mail's PGP encryption page.
Unfortunately, there is no open source email client for iPhone that supports PGP encryption. In fact, there does not seem to be any open source iPhone email client at all! Apple has always demanded that their users stick with their ecosystem and with email, they have pretty much succeeded. While it is possible to use Apple's proprietary mail app to connect to EzIsland, sending and receiving PGP encrypted emails is not possible without spending money on a the proprietary iPG-Mail app. Even then, this app is unlikely to integrate well with EzIsland and probably won't play well with the GNU PGP implementation that Thunderbird, K-9 Mail, and essentially all other open source mail clients use.
In general, any software relating to security and esppecially to encryption should never be trusted when it is closed source and proprietary. These are critical components to cryptography and a mistake or an malicious backdoor in Apple's implementation of PGP could be catastrophic. Further, mistakes could be intentionally hidden by Apple and backdoors may go unnoticed for years since no one has access to the source code. That's why users should avoid using the iPhone for sending and receiving mail, especially if they want to encrypt that mail.