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

In your app/build.gradle file you need to

1. Upgrade to newer version of the mail API (at least 1.6.6):

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

2. exclude these files in packagingOptions:

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

source

Using Gradle Kotlin DSL with Version Catalog:

app/build.gradle.kts

android {
    ...
    packaging {
        resources {
            excludes += listOf("META-INF/NOTICE.md", "META-INF/LICENSE.md")
        }
    }
}

dependencies {
    implementation(libs.jakarta.mail)
    implementation(libs.jakarta.mail.activation)
    ...
}

gradle/libs.versions.toml

[versions]
jakarta-mail = "1.6.6"
...

[libraries]
jakarta-mail = { module = "com.sun.mail:android-mail", version.ref = "jakarta-mail" }
jakarta-mail-activation = { module = "com.sun.mail:android-activation", version.ref = "jakarta-mail" }
...