How to Send Encrypted Email on iPhone and Android

Introduction

Ever had that gut feeling right before hitting “Send” on an important email, wondering who might actually see what you just wrote? You’re not alone. In today’s world of constant data breaches and digital snooping, making sure your emails are private isn’t just smart, it’s necessary.

That’s where encrypted email comes in. It’s your virtual lockbox. Whether you’re sharing sensitive client details, personal documents, or even just want some peace of mind, encryption ensures that only the intended person can read your message.

The good news is, sending encrypted email from your trusty iPhone or Android device is more accessible than you might think.

 While it might seem a tad daunting at first, I’m here to walk you through it, making the process as clear as possible. We’ll explore the two main roads you can take: the built-in solutions for iPhone and the robust third-party options for Android.

What Is Encrypted Email, Exactly?

Encrypted email means your message gets scrambled into unreadable text as it travels to your recipient. Only the person with the right key can unscramble it. So, if a hacker, or anyone else, intercepts it mid-transit, all they’ll see is gibberish.

Why Bother with Encrypted Email? 

Before we dive into the “how,” let’s just take a moment to understand the “why.” You might be thinking, “My emails are just mundane, who’d want to read them?” But the reality is, your digital footprint is valuable, and even seemingly innocuous details can be pieced together.

Consider this,  in 2022, the global email subscriber count reached approximately 4.26 billion and is anticipated to rise to nearly 4.73 billion by 2026. With such widespread adoption, email remains a significant cybersecurity vulnerability. 

Reports indicate that about 94% of malware was transmitted through email in 2021, and phishing remains a leading method of email attacks. These aren’t just statistics; they represent real threats to your privacy and security.

An email, when not encrypted, travels in plain text. Imagine it as a conversation shouted across a crowded market. Anyone can overhear it. Encryption transforms that shout into a coded whisper that only the person with the “key” can understand.

How to Send Encrypted Email on iPhone

If you’re an iPhone user, you have a few solid options. Apple’s built-in Mail app already supports encryption, if you’re willing to put in a little setup work. Otherwise, there are encrypted email apps that make everything automatic.

Using Apple’s Built-in S/MIME Support

As an iPhone user, you’re in a somewhat privileged position when it comes to email encryption. Your device has a built-in feature called S/MIME (Secure/Multipurpose Internet Mail Extensions), which is a fantastic starting point. Think of S/MIME as a digital envelope and seal provided by a trusted authority.

However, to use S/MIME, you’ll need something called an S/MIME certificate. This certificate essentially acts as your digital ID card, verifying your identity and containing the public key needed for others to encrypt messages to you, and your private key to decrypt messages from you.

Getting Your S/MIME Certificate: Your Digital ID Card

This is often the trickiest part for individuals. You can obtain an S/MIME certificate in a few ways:

• Purchase from a Certificate Authority (CA): These are organizations that issue digital certificates. Some even offer basic S/MIME certificates for free, so it’s worth looking around.
• Through Your Organization: If you use an Exchange email account (common in corporate environments), your IT department might provide and manage an S/MIME certificate for you. This is often the smoothest route.

Once you have your certificate, it will usually be a .p12 or .pfx file. This file contains your private key, so treat it like gold and keep it secure. It’s often password-protected too, another layer of security!

Installing the Certificate on Your iPhone

This process is surprisingly straightforward:

1. Transfer the file to your iPhone. The easiest ways are often through AirDrop, iCloud Drive, or even by emailing the file to yourself (just remember to delete the email after installation!).
2. Tap the .p12 or .pfx file. Your iPhone should recognize it and prompt you to install a profile.
3. Head to Settings. You’ll likely see a “Profile Downloaded” option right at the top. If not, navigate to Settings > General > VPN & Device Management.
4. Tap “Install” and enter your device passcode.
5. Enter the password you set for the .p12 file 
6. Finally, tap Done. Your digital ID is now loaded!

Enabling S/MIME in Your Mail App: The Final Setup

Now that your certificate is installed, you need to tell your Mail app to use it:

1. Open Settings on your iPhone.
2. Scroll down and tap Mail, then Accounts.
3. Select the email account where you installed the S/MIME certificate.
4. Tap Account (or the account name again) and then Advanced.
5. You’ll see an S/MIME option. Toggle it to On.
6. Two new options will appear: “Sign” and “Encrypt by Default.”
   • Sign: I highly recommend turning this on. It digitally “signs” your emails, essentially putting your verified signature on them. This assures recipients that the email truly came from you and hasn’t been tampered with.
   • Encrypt by Default: You can turn this on if you want all outgoing emails from this account to be encrypted by default. However, remember, encryption only works if the recipient also has an S/MIME setup and you have their public key!

Sending Encrypted Emails on Your iPhone

With S/MIME enabled, composing an email in the Mail app becomes a subtly different experience:

• When you start a new email, look closely at the address field. You’ll notice a blue Lock icon.
• This icon is your indicator. If the recipient also has S/MIME set up and your iPhone has their public key (which often happens automatically if they send you a digitally signed email), the lock will appear closed (blue and locked). This means your email will be encrypted for them.
• If the lock is open, it means the email won’t be encrypted for that particular recipient, likely because your device doesn’t have their public key.
• You can usually tap the lock icon to manually toggle the encryption state for individual messages.

A crucial point here: S/MIME encryption relies on knowing the recipient’s public key. It’s a bit like needing their specific mailbox key to drop your sealed letter into. If they send you a signed email, your iPhone usually smart enough to grab and store their public key. In corporate Exchange environments, this often happens seamlessly as the system can fetch certificates from the Global Address List.

The Android Way: Powering Up with Third-Party Apps

Android, being more open, takes a slightly different approach to encrypted email, primarily leaning on the widely adopted PGP (Pretty Good Privacy) or its open-source counterpart, OpenPGP. While there isn’t a universally built-in S/MIME equivalent like on iOS, the ecosystem of third-party apps offers incredible flexibility and robust security.

Think of PGP as a sophisticated encryption kit you can bolt onto your existing email experience. It gives you full control over your keys and encryption.

OpenKeychain and K-9 Mail

For many Android users, the combination of OpenKeychain (for managing your encryption keys) and K-9 Mail (an email client that integrates with OpenKeychain) is a powerhouse.

Setting Up Your PGP/OpenPGP Encryption:

1. Install OpenKeychain: Head to the Google Play Store and download “OpenKeychain: Easy PGP.” This app is your central hub for generating, importing, and managing your encryption keys.
2. Generate or Import Your PGP Key:
   • Open OpenKeychain.
   • If you’re new to PGP, you’ll want to create a new key. The app will guide you through generating a unique pair of keys: a public key, which you share with others and a private key which you keep secret and secure.
   • If you already have a PGP key from another system, you can import an existing key file.
3. Install K-9 Mail: Again, from the Google Play Store, download “K-9 Mail.” It’s a popular, highly configurable open-source email client.
4. Configure Your Email Account in K-9 Mail: Set up your email account in K-9 Mail just as you would any other email client.
5. Enable OpenPGP Support in K-9 Mail: This is where the magic happens, connecting K-9 Mail to OpenKeychain.
   • In K-9 Mail, go to Settings > Account settings, select the account you want to encrypt.
   • Look for a section often labeled Cryptography or End-to-end encryption.
   • Choose OpenKeychain as your PGP app.
   • Select the PGP key you generated or imported in OpenKeychain for this specific email account.

Sharing Public Keys

Just like with S/MIME, to send an encrypted email with PGP, you need the recipient’s public PGP key. This is a fundamental concept in public-key cryptography.

• You’ll need to ask your recipient to send you their public PGP key. They can typically export it from their OpenKeychain app or other PGP software.
• Once you receive it, you can import it into your OpenKeychain app. OpenKeychain also often allows you to search for public keys on global key servers, which can be super convenient.

Sending Encrypted Emails on Android with K-9 Mail:

• When you compose a new email in K-9 Mail, you’ll typically see a padlock icon (much like on iOS).
• Tap the padlock icon to enable encryption for that message.
• If your OpenKeychain app has the recipient’s public key, and it’s trusted, K-9 Mail will indicate that the message will be encrypted.
• You might be prompted to enter your PGP passphrase, the password for your private key  to sign and/or encrypt the message.

Gmail’s “Confidential Mode”: A Different Kind of Privacy

While not true end-to-end encryption in the same vein as S/MIME or PGP, meaning Google still has access to your message content, Gmail’s “Confidential Mode” offers a useful layer of control over your messages. It’s more about managing access and preventing unwanted distribution.

How it works: Confidential Mode lets you set an expiration date for your email and prevent recipients from forwarding, copying, printing, or downloading the message. It’s a great option for sending sensitive but not top-secret information.

Using Gmail’s Confidential Mode on Android:

1. Open the Gmail app on your Android device.
2. Tap the Compose button (the plus sign).
3. In the top right corner, tap the More icon (three vertical dots).
4. Select Confidential mode.
5. Toggle Confidential mode on.
6. You can then set an expiration date (from one day to five years) and choose a passcode requirement.
   • Standard: Recipients using the Gmail app will open it directly. Those not using Gmail will get an email with a passcode that will be sent to them directly.
   • SMS passcode: This is more secure. The recipient will receive a passcode via a text message to their phone number. You’ll need to enter their phone number when setting this up.
7. Tap Done (the checkmark).
8. Compose your email as usual and send it.

A Word of Caution about Confidential Mode

 It’s important to remember that while Confidential Mode restricts actions like forwarding, it doesn’t prevent a determined recipient from taking a screenshot or a photo of the message. It’s a good privacy enhancement, but not a full encryption solution.

Beyond the Basics: Dedicated Encrypted Email Services

If the above methods feel a bit too technical, or you’re seeking a more integrated, seamless end-to-end encrypted experience, several dedicated secure email providers are excellent choices. They build encryption directly into their services, often offering user-friendly apps for both iPhone and Android.

Proton Mail

This is perhaps the most well-known. Based in Switzerland, Proton Mail offers end-to-end encryption for all emails, ensuring only the sender and recipient can read them. Their apps are intuitive and widely praised for their security features.

Tuta Mail

Another strong contender, Tuta Mail (formerly Tutanota) focuses on privacy by encrypting all your data, emails, calendars, and contacts by default. They have excellent apps for both mobile platforms.

Mailfence

A secure email provider based in Belgium, Mailfence offers OpenPGP-based encryption and digital signatures, giving you robust control over your communication security.

These services essentially handle the complexities of key management and encryption behind the scenes, offering a “set it and forget it” approach to secure communication. They are particularly appealing if you’re starting fresh with a new email address and want privacy by design.

Conclusion

In an era where data breaches are becoming alarmingly common ,  the email encryption market is projected to grow significantly, reaching an estimated USD 40.16 billion by 2033, driven largely by the increasing number of email data breaches ,  taking proactive steps to secure your communications is paramount. 

Whether you choose to dive into the world of S/MIME on your iPhone, leverage the power of PGP with third-party apps on Android, or opt for a dedicated secure email service, the important thing is to make a conscious choice for your privacy.

So, go ahead, empower yourself. Add that digital padlock to your emails. Your private conversations deserve to stay private, and with these tools, they absolutely can.

Ready to take control of your privacy?

Understanding how to send encrypted email on iPhone and Android is just the first step. True security comes from turning these habits into a well-oiled system.

Download our free Security Checklist, packed with easy-to-follow tips and real-world examples to help you and your team implement secure, private communication, no matter what device you use.

Still feeling unsure about which tools or methods are right for your setup? Book a free consultation with our privacy experts. We’ll walk you through your options, help you untangle any technical knots, and recommend what fits best for your goals and budget.

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