Android Studio VerifyError rejecting class text_plain from JavaMail API

Question

I'm developing an application that allows the user to contact me by sending an email (the user only inputs the message, sender and receiver emails are both mine). I'm trying to implement this with gmail using the JavaMail API. However, I keep getting this error at the Transport.send(mimeMessage) line.

Here are the error messages:

Caused by: java.lang.VerifyError: Rejecting class com.sun.mail.handlers.text_plain that attempts to sub-type erroneous class com.sun.mail.handlers.handler_base (declaration of 'com.sun.mail.handlers.text_plain' appears in /data/app/~~T_TRkO9R_v9j4iEdr4K9Yg==/com.example.compusec-dPeAL8DtGJvU45dJpt8xxA==/base.apk)

Caused by: java.lang.VerifyError: Verifier rejected class com.sun.mail.handlers.handler_base: java.awt.datatransfer.DataFlavor[] com.sun.mail.handlers.handler_base.getTransferDataFlavors() failed to verify: java.awt.datatransfer.DataFlavor[] com.sun.mail.handlers.handler_base.getTransferDataFlavors(): [0x4] can't resolve returned type 'Unresolved Reference: java.awt.datatransfer.DataFlavor[]' or 'Reference: javax.activation.ActivationDataFlavor[]' (declaration of 'com.sun.mail.handlers.handler_base' appears in /data/app/~~T_TRkO9R_v9j4iEdr4K9Yg==/com.example.compusec-dPeAL8DtGJvU45dJpt8xxA==/base.apk)

Here is my code:

    protected Void doInBackground(Void... voids) {
        Properties properties = new Properties();
        properties.put("mail.smtp.host", "smtp.gmail.com");
        properties.put("mail.smtp.socketFactory.port", "465");
        properties.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        properties.put("mail.smtp.auth", "true");
        properties.put("mail.smtp.port", "465");

        session = javax.mail.Session.getInstance(properties, new javax.mail.Authenticator(){
            protected PasswordAuthentication getPasswordAuthentication(){
                return new PasswordAuthentication("[email protected]","senderpass");
            }
        });

        session.setDebug(true);

        MimeMessage mimeMessage = new MimeMessage(session);
        try {
            mimeMessage.setFrom(new InternetAddress("[email protected]"));
            mimeMessage.addRecipients(Message.RecipientType.TO, String.valueOf(new InternetAddress(email)));
            mimeMessage.setSubject(subject);
            mimeMessage.setText(message);
            Transport.send(mimeMessage);
        } catch (MessagingException e) {
            e.printStackTrace();
        }

        return null;
    }

And the gradle script:

plugins {
    id 'com.android.application'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.2"

    packagingOptions {
        pickFirst 'META-INF/LICENSE.txt' // picks the JavaMail license file
    }

    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 23
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

repositories {
    jcenter()
    maven {
        url "https://maven.java.net/content/groups/public/"
    }
}

dependencies {

    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'com.google.android.material:material:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    compile 'com.sun.mail:android-mail:1.6.2'
    compile 'com.sun.mail:android-activation:1.6.2'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
}

Answer 1

I am having the same issue. What I can tell you is that if you target Android 10 and lower (SDK 29 or lower) it works fine. I have been using it for years. However, as soon as I target Android 11 (SDK 30) then I get this error. My guess is com.sun.mail dependencies need to be updated. I'm using the latest 1.6.5 and still doesn't work. So I suggest targeting SDK 29 for now and see if that helps.

Answer 2

Use this in build.gradle:

android {
    ...
    packagingOptions {
        exclude 'META-INF/NOTICE.md'
        exclude 'META-INF/LICENSE.md'
    }
}

dependencies {
    implementation 'com.sun.mail:android-mail:1.6.6'
    implementation 'com.sun.mail:android-activation:1.6.6'
    ...
}

credit to last few comments on this issue

Answer 3

My answer here, that is in-line with other answers (as that answer explains), does provide a solution (I'll skip to the content here, details can be read there);

The issue:

API level 30 adds a new (verifier) feature that verifies that all referenced code actually exists - or fails a build.

To resolve::

1. If you were providing the libraries manually via /app/libs/mail.jar, /app/libs/activation.jar, and /app/libs/additionnal.jar - you can go ahead and remove them; both google() and maven() repositories are enabled in Android projects, and the latest deps are available there. They include new META-INF files, so go we'll also need to remove them from the build when we update the deps;

to your project-level gradle file (/build.gradle):

buildscript {
    ext {
        // ...
        java_mail_version = "1.6.7"
    }
    // ...
}

// ...

to your app/module-level gradle file (/app/build.gradle):

    //...
android {
    // ...
    packagingOptions {
        resources {
            excludes += '/META-INF/{AL2.0,LGPL2.1}'
            excludes += '/META-INF/{NOTICE.md,LICENSE.md}' // <-- This line
        }
    }
}
    // ...
dependencies {
    // ...

    // Dumb Email Sending
    implementation "com.sun.mail:android-mail:$java_mail_version"

    // REMOVE THESE - DEPS WILL DOWNLOAD AUTOMATICALLY
    //implementation 'com.sun.mail:android-activation:1.6.7' // from 1.6.4
    //implementation 'com.sun.mail:android-additionnal:1.6.7' // from 1.6.4
}

// ...

That's it, issue resolved on API Level 30 - and no more lugging the .jar files around (if you were).