* [JavaMail](https://projects.eclipse.org/projects/ee4j.javamail). Copyright (c) 1997-2018 Oracle® and/or its affiliates. All rights reserved. [GPLv2+CE license](https://javaee.github.io/javamail/JavaMail-License).
* [Android Support Library](https://developer.android.com/tools/support-library/). Copyright (C) 2011 The Android Open Source Project. [Apache license 2.0](https://android.googlesource.com/platform/frameworks/support/+/master/LICENSE.txt).
* [Android Architecture Components](https://developer.android.com/topic/libraries/architecture/). Copyright 2018 The Android Open Source Project, Inc. [Apache license 2.0](https://github.com/googlesamples/android-architecture-components/blob/master/LICENSE).
* [dnsjava](http://www.xbill.org/dnsjava/). Copyright (c) 1998-2011, Brian Wellington. [BSD License](https://sourceforge.net/p/dnsjava/code/HEAD/tree/trunk/LICENSE).
* [Bouncy Castle](https://www.bouncycastle.org/). Copyright (c) 2000 - 2019 The Legion of the Bouncy Castle Inc. [MIT License](https://www.bouncycastle.org/licence.html).