How to send encrypted emails on iPhone or Android phone

Make your emails messages private by encrypting them

Be careful what you say in emails, they may not be secure and could be read by others. Here is how to send encrypted emails that are secure and unreadable by others using just your phone.

Are emails encrypted? Some emails are, but some are not and it depends on which email service is being used. It also depends on the settings and even if encryption is available, it is not always used unless it is selected by enabling an option or using a switch or button.

Encryption is actually complicated when it comes to emails and you have to understand how emails are sent to realize the problem. When emails are sent, they are passed to an email server using secure communications, a bit like the way https connections work with websites. That is great and if someone intercepted an email on its journey, they would not be able to read it.

Emails bounce from mail server to mail server until they reach your own email server and there they wait for you to fetch them. Although email is encrypted while travelling between servers on the internet, at each server on the journey from sender to your computer, it is decrypted and stored as plain text. That is a risk.

It is not easy to intercept email communications and read the contents, but it is certainly possible with the right tools to access mail at the points it is decrypted and you should avoid sending private information. You are relying on the privacy and security of each server along the way and you just cannot guarantee it.

End-to-end email encryption

The solution is end-to-end encryption. An email is encrypted on the computer or phone before it is sent and decrypted on the computer or phone of the recipient. Even if it passes through insecure mail servers along the route, it cannot be read because it is encrypted.

There are several ways to encrypt emails so that only you and the recipient can read them and here I look at sending encrypted emails using ProtonMail on a phone. One ProtonMail user sending an email to another ProtonMail user is always encrypted by default and at no time can it be read by anyone other than the recipient, but what about ProtonMail to Gmail or Outlook? Yes, that can be encrypted too and I show this below.

ProtonMail can be used for free on the web and free apps are available for the iPhone and Android phone in the app stores. They work the same on iOS and Android. There are some limits with a free account, like only 500 MB of storage and three folders or labels, but it is a great way to send encrypted, private emails. Let’s take a look.

1 Open the ProtonMail app

ProtonMail email app on an Android phone

I am using an Android phone, but this works just the same on an iPhone. I am also using a free ProtonMail account, but this also works with a paid account. Open ProtonMail and click the pencil icon to create a new email message.

2 Create an email

Writing an email in the ProtonMail app on a phone

Fill in the To box, enter a subject line, write the email and when you have finished, click the padlock icon in the toolbar. This enables the email to be locked. If you are sending the email to another ProtonMail user, you can simply click the Send button and don’t need to bother with the rest of the steps, you are done. Read on to see how to send encrypted emails to non-ProtonMail users.

3 Set a password

Encrypting a ProtonMail email using the phone app

Clicking the padlock enables a password to be entered. There is an optional password hint at the bottom and this can be used to jog the recipient’s memory when they receive the message. ProtonMail to ProtonMail emails are always end-to-end encrypted and are therefore secure. This password is just for those occasions when you want to send an encrypted email to someone not on ProtonMail, such as an Outlook, Gmail user or other email account.

4 Send the encrypted email

Sending an encrypted email using the Protonmail app

The email is ready to be sent. You can tell it is encrypted because of the tick on the padlock. This is required only for external encrypted emails, internal ones are always encrypted. Click the button in the top right corner to send the message.

5 Receive an encrypted email

Receiving a ProtonMail encrypted email in Gmail on a phone

This is what it looks like to receive an encrypted email from a ProtonMail user. It is Gmail on an Android phone, but it will look the same in any email app. No part of the message subject or body can be seen, only who it is from. There is a button to view the message and the recipient has about 4 weeks before it expires. Click View Message.

6 Read an encrypted email

Reading an encrypted email from a ProtonMail user

A new screen appears and the recipient must enter the password to decrypt the message. You, the sender, must somehow pass this on to the recipient securely by other means. The pair of you can agree on a password before you start emailing each other and always use the same one if you like. When the keyboard pops up, as in the screenshot, it covers the password hint, but it is there.

7 Read and reply to encrypted emails

Reading an encrypted email from a ProtonMail user

The encrypted message is displayed after entering the password. Emails received by ProtonMail are permanent as all emails should be, but an encrypted email outside of ProtonMail, received by Outlook, Gmail or some other email service, has an expiry date. (Non-encrypted emails do not expire.)

The recipient of the email can reply securely by clicking the button at the top.

8 Reply to encrypted emails

Sending an encrypted email reply using ProtonMail

A simple Rich Text editor is displayed and a reply to the email can be entered and the Send button used to finish. The reply is encrypted and sent to the ProtonMail user.

Neither the email nor the reply are kept in the recipients email account – Gmail, Outlook or wherever. If the recipient wanted to keep the email, they would need to copy it and save it. This is a problem for encrypted email conversations between ProtonMail users and Gmail, Outlook and other users. You, as a ProtonMail user can see all emails. They cannot.

If you want to have a conversation with an external email user and the topic does not contain anything secret, do not use ProtonMail encryption. The email is then sent normally. For private information, encrypt it, but be aware that the recipient can only access the email for a month and they cannot see the conversation in their email app.

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About Anthony Waddilove 50 Articles
I have been a computer, phone and internet enthusiast for many years. This has enabled me to build up an extensive knowledge about them. I still have a lot to learn, but I am working hard at it!