K9 is a stable and popular email client for Android mobile devices.
A free software project created by a strong community of volunteers, K9 makes it easy to add multiple accounts and to deal with large amounts of incoming emails. It has recently added support for GPG encryption, which is a common way of sending encrypted messages.
For more information about encryption, consult Tactical Tech's Security-in-a-box guide.
Sending encrypted messages about sensitive information from mobile phones.
Allows a well-tested form of encrypted communication to be used on Android mobile devices.
If your phone is taken then your private key is also taken. You would need to revoke it and create a new one.
Only works on Android phones and can be tricky to set up if you are new to using encryption.
Requires APG to be installed for PGP encryption to work.