How to Send Encrypted Email on Android

For the most part, encryption sounds like the reserve of government agencies, criminal court cases and movies about hackers trying to break into big businesses and banks. But encryption operates in all areas of our online experience – from website forms to Google Drive documents.

That said, much of the encryption protection in place on your Gmails and your Outlooks covers HTTPS, and usually not SMTP, which means that spy agencies or other unwelcome eyes can still snoop on you via sneaky backdoors. Here’s a quick method for your Android device that will ensure your emails are encrypted all the way from one end to the other.


This lightweight app keeps the whole encryption process nice and simple. What I like about it is that it doesn’t force you to use its own email app because it’s basically a notepad that encrypts whatever you type into it, then you copy-paste the information into your favorite email app (or any other kind of written communications app). Yep, that means you can use the nice and intuitive Gmail app and have everything you write encrypted. Having your cake and codifying it.

Download CryptMax from the Play Store, open it, and you’ll be presented with a black screen on which to type your message. There is only one option you really need to think about here.


AES-128 vs. AES-192 vs. AES-256

The most notable variable in CryptMax is the “AES-128” at the top-right which is the strength of the encryption method you’re using. Tapping this will toggle the encryption method to AES-192 or AES-256, which are technically more secure than 128, but in reality even an AES-128-encrypted message would be almost impossible to break. Some tests have even shown that AES-256 can be more vulnerable to certain kinds of attacks, though even this hasn’t been practically proven yet. While government agencies and other big organizations go for 192 or 256, there is no practical way to even break AES-128 encryption at this point.

In short, stick with AES-128 – you’ll be fine.


Sending and Receiving an Encrypted Message

In CryptMax, once you’ve written your email, type a password for it below the text box. The recipient will need this password and the CryptMax app in order to be able to read the message. You should make this password secure because if someone manages to break this, they’ll be able to decrypt your message (assuming, of course, that they’re targeting you and know that you’re using CryptMax, which is all pretty unlikely).

Once you’ve created a password, tap “Encrypt” at the bottom-left, which will turn the text into garbled encrypted code. Next, tap “Copy,” then go to whatever email app you want to send the message from, long-tap in the body area of the message, then tap “Paste.” The encrypted text should appear, and it’s then ready to send.


Again, remember that when the recipient receives the email, they’ll need to copy-paste the garbled text into CryptMax and use your password to read it. It’s a bit of work, sure, but that’s the price you pay for top security!


AES encryption remains by far the best way to make sure that your private messages remain private. If you don’t like the whole copy-paste process, you can use something like K-9 Mail alongside APG (Android Privacy Guard) to send encrypted emails directly, but if you like the interfaces of whichever app you’re currently using, then CryptMax remains your best bet.

Robert Zak
Robert Zak

Content Manager at Make Tech Easier. Enjoys Android, Windows, and tinkering with retro console emulation to breaking point.

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