我为其他需要帮助的人找到了一个更短的选择。代码是:

package com.example.mail;

import java.util.Properties;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendMailTLS {

    public static void main(String[] args) {

        final String username = "username@gmail.com";
        final String password = "password";

        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "587");

        Session session = Session.getInstance(props,
          new javax.mail.Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, password);
            }
          });

        try {

            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("from-email@gmail.com"));
            message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("to-email@gmail.com"));
            message.setSubject("Testing Subject");
            message.setText("Dear Mail Crawler,"
                + "\n\n No spam to my email, please!");

            Transport.send(message);

            System.out.println("Done");

        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }
}

来源:通过JavaMail API发送电子邮件

希望这能有所帮助!好运！

编辑:JavaMail 1.5.5声称支持Android，所以你不需要其他任何东西。

我已经将最新的JavaMail(1.5.4)移植到Android。它可以在Maven Central中获得，只需添加以下内容到build.gradle~~

compile 'eu.ocathain.com.sun.mail:javax.mail:1.5.4'

然后你就可以按照官方教程学习了。

源代码可以在这里找到:https://bitbucket.org/artbristol/javamail-forked-android

如果你被要求保持jar库尽可能小，你可以分别包含SMTP/POP3/IMAP功能，以避免“dex中有太多方法”的问题。

您可以在javanet网页上选择需要的jar库，例如mailapi.jar + IMAP .jar可以让您在IMAP协议下访问icloud、hotmail邮件服务器。(在additional.jar和activate .jar的帮助下)

对于那些想在2020年与Kotlin一起使用JavaMail的人:

首先:将这些依赖项添加到构建中。gradle文件(官方JavaMail Maven依赖项)

实现“com.sun.mail: android-mail: 1.6.5” 实现“com.sun.mail: android激活:1.6.5”

实现“org.bouncycastle: bcmail-jdk15on: 1.65” 实现“org.jetbrains.kotlinx: kotlinx-coroutines-core: 1.3.7” 实现“org.jetbrains.kotlinx: kotlinx-coroutines-android: 1.3.7”

BouncyCastle是出于安全考虑。

第二步:将这些权限添加到AndroidManifest.xml中

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

第三:当使用SMTP时，创建一个配置文件

object Config {
    const val EMAIL_FROM = "You_Sender_Email@email.com"
    const val PASS_FROM = "Your_Sender_Password"

    const val EMAIL_TO = "Your_Destination_Email@email.com"
}

第四:创建Mailer对象

object Mailer {

init {
    Security.addProvider(BouncyCastleProvider())
}

private fun props(): Properties = Properties().also {
        // Smtp server
        it["mail.smtp.host"] = "smtp.gmail.com"
        // Change when necessary
        it["mail.smtp.auth"] = "true"
        it["mail.smtp.port"] = "465"
        // Easy and fast way to enable ssl in JavaMail
        it["mail.smtp.ssl.enable"] = true
    }

// Dont ever use "getDefaultInstance" like other examples do!
private fun session(emailFrom: String, emailPass: String): Session = Session.getInstance(props(), object : Authenticator() {
    override fun getPasswordAuthentication(): PasswordAuthentication {
        return PasswordAuthentication(emailFrom, emailPass)
    }
})

private fun builtMessage(firstName: String, surName: String): String {
    return """
            <b>Name:</b> $firstName  <br/>
            <b>Surname:</b> $surName <br/>
        """.trimIndent()
}

private fun builtSubject(issue: String, firstName: String, surName: String):String {
    return """
            $issue | $firstName, $surName
        """.trimIndent()
}

private fun sendMessageTo(emailFrom: String, session: Session, message: String, subject: String) {
    try {
        MimeMessage(session).let { mime ->
            mime.setFrom(InternetAddress(emailFrom))
            // Adding receiver
            mime.addRecipient(Message.RecipientType.TO, InternetAddress(Config.EMAIL_TO))
            // Adding subject
            mime.subject = subject
            // Adding message
            mime.setText(message)
            // Set Content of Message to Html if needed
            mime.setContent(message, "text/html")
            // send mail
            Transport.send(mime)
        }

    } catch (e: MessagingException) {
        Log.e("","") // Or use timber, it really doesn't matter
    }
}

fun sendMail(firstName: String, surName: String) {
        // Open a session
        val session = session(Config.EMAIL_FROM, Config.PASSWORD_FROM)

        // Create a message
        val message = builtMessage(firstName, surName)

        // Create subject
        val subject = builtSubject(firstName, surName)

        // Send Email
        CoroutineScope(Dispatchers.IO).launch { sendMessageTo(Config.EMAIL_FROM, session, message, subject) }
}

Note

If you want a more secure way to send your email (and you want a more secure way!), use http as mentioned in the solutions before (I will maybe add it later in this answer) You have to properly check, if the users phone has internet access, otherwise the app will crash. When using gmail, enable "less secure apps" (this will not work, when you gmail has two factors enabled) https://myaccount.google.com/lesssecureapps?pli=1 Some credits belong to: https://medium.com/@chetan.garg36/android-send-mails-not-intent-642d2a71d2ee (he used RxJava for his solution)

 Add jar files mail.jar,activation.jar,additionnal.jar

 String sub="Thank you for your online registration" ; 
 Mail m = new Mail("emailid", "password"); 

 String[] toArr = {"ekkatrainfo@gmail.com",sEmailId};
 m.setFrom("ekkatrainfo@gmail.com"); 

     m.setTo(toArr);
     m.setSubject(sub);
    m.setBody(msg);



                     try{


                            if(m.send()) { 

                            } else { 

                            } 
                          } catch(Exception e) { 

                            Log.e("MailApp", "Could not send email", e); 
                          } 

  package com.example.ekktra;

   import java.util.Date;
   import java.util.Properties;

   import javax.activation.CommandMap;
   import javax.activation.DataHandler;
   import javax.activation.DataSource;
   import javax.activation.FileDataSource;
   import javax.activation.MailcapCommandMap;
   import javax.mail.BodyPart;
   import javax.mail.Multipart;
   import javax.mail.PasswordAuthentication;
   import javax.mail.Session;
   import javax.mail.Transport;
   import javax.mail.internet.InternetAddress;
   import javax.mail.internet.MimeBodyPart;
   import javax.mail.internet.MimeMessage;
   import javax.mail.internet.MimeMultipart;

   public class Mail extends javax.mail.Authenticator { 
     private String _user; 
     private String _pass; 

     private String[] _to; 

     private String _from; 

     private String _port; 
     private String _sport; 

     private String _host; 

     private String _subject; 
     private String _body; 

     private boolean _auth; 

     private boolean _debuggable; 

     private Multipart _multipart; 


   public Mail() { 
      _host = "smtp.gmail.com"; // default smtp server 
      _port = "465"; // default smtp port 
      _sport = "465"; // default socketfactory port 

      _user = ""; // username 
      _pass = ""; // password 
      _from = ""; // email sent from 
      _subject = ""; // email subject 
      _body = ""; // email body 

      _debuggable = false; // debug mode on or off - default off 
      _auth = true; // smtp authentication - default on 

      _multipart = new MimeMultipart(); 

      // There is something wrong with MailCap, javamail can not find a handler for the        multipart/mixed part, so this bit needs to be added. 
      MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap(); 
   mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html"); 
   mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml"); 
   mc.addMailcap("text/plain;; x-java-content-  handler=com.sun.mail.handlers.text_plain"); 
   mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed"); 
   mc.addMailcap("message/rfc822;; x-java-content- handler=com.sun.mail.handlers.message_rfc822"); 
    CommandMap.setDefaultCommandMap(mc); 
   } 

 public Mail(String user, String pass) { 
  this(); 

  _user = user; 
   _pass = pass; 
 } 

public boolean send() throws Exception { 
   Properties props = _setProperties(); 

  if(!_user.equals("") && !_pass.equals("") && _to.length > 0 && !_from.equals("") &&   !_subject.equals("") /*&& !_body.equals("")*/) { 
    Session session = Session.getInstance(props, this); 

    MimeMessage msg = new MimeMessage(session); 

     msg.setFrom(new InternetAddress(_from)); 

    InternetAddress[] addressTo = new InternetAddress[_to.length]; 
     for (int i = 0; i < _to.length; i++) { 
      addressTo[i] = new InternetAddress(_to[i]); 
    } 
      msg.setRecipients(MimeMessage.RecipientType.TO, addressTo); 

    msg.setSubject(_subject); 
    msg.setSentDate(new Date()); 

  // setup message body 
  BodyPart messageBodyPart = new MimeBodyPart(); 
    messageBodyPart.setText(_body); 
    _multipart.addBodyPart(messageBodyPart); 

     // Put parts in message 
    msg.setContent(_multipart); 

    // send email 
    Transport.send(msg); 

    return true; 
   } else { 
     return false; 
   } 
  } 

   public void addAttachment(String filename) throws Exception { 
    BodyPart messageBodyPart = new MimeBodyPart(); 
    DataSource source = new FileDataSource(filename); 
      messageBodyPart.setDataHandler(new DataHandler(source)); 
    messageBodyPart.setFileName(filename); 

   _multipart.addBodyPart(messageBodyPart); 
 } 

  @Override 
  public PasswordAuthentication getPasswordAuthentication() { 
     return new PasswordAuthentication(_user, _pass); 
  } 

   private Properties _setProperties() { 
   Properties props = new Properties(); 

    props.put("mail.smtp.host", _host); 

  if(_debuggable) { 
    props.put("mail.debug", "true"); 
  } 

  if(_auth) { 
    props.put("mail.smtp.auth", "true"); 
   } 

    props.put("mail.smtp.port", _port); 
    props.put("mail.smtp.socketFactory.port", _sport); 
    props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory"); 
    props.put("mail.smtp.socketFactory.fallback", "false"); 

    return props; 
   } 

   // the getters and setters 
  public String getBody() { 
   return _body; 
 } 

 public void setBody(String _body) { 
  this._body = _body; 
 }

  public void setTo(String[] toArr) {
     // TODO Auto-generated method stub
    this._to=toArr;
 }

public void setFrom(String string) {
    // TODO Auto-generated method stub
    this._from=string;
}

 public void setSubject(String string) {
    // TODO Auto-generated method stub
    this._subject=string;
  }  


   }

在Android中使用JavaMail API使用Gmail身份验证发送电子邮件。

创建示例项目的步骤:

MailSenderActivity.java:

public class MailSenderActivity extends Activity {
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        final Button send = (Button) this.findViewById(R.id.send);
        send.setOnClickListener(new View.OnClickListener() {
            
            public void onClick(View v) {
                try {   
                    GMailSender sender = new GMailSender("username@gmail.com", "password");
                    sender.sendMail("This is Subject",   
                            "This is Body",   
                            "user@gmail.com",   
                            "user@yahoo.com");   
                } catch (Exception e) {   
                    Log.e("SendMail", e.getMessage(), e);   
                } 
                
            }
        });
        
    }
}

GMailSender.java:

public class GMailSender extends javax.mail.Authenticator {   
    private String mailhost = "smtp.gmail.com";   
    private String user;   
    private String password;   
    private Session session;   
  
    static {   
        Security.addProvider(new com.provider.JSSEProvider());   
    }  
  
    public GMailSender(String user, String password) {   
        this.user = user;   
        this.password = password;   
  
        Properties props = new Properties();   
        props.setProperty("mail.transport.protocol", "smtp");   
        props.setProperty("mail.host", mailhost);   
        props.put("mail.smtp.auth", "true");   
        props.put("mail.smtp.port", "465");   
        props.put("mail.smtp.socketFactory.port", "465");   
        props.put("mail.smtp.socketFactory.class",   
                "javax.net.ssl.SSLSocketFactory");   
        props.put("mail.smtp.socketFactory.fallback", "false");   
        props.setProperty("mail.smtp.quitwait", "false");   
  
        session = Session.getDefaultInstance(props, this);   
    }   
  
    protected PasswordAuthentication getPasswordAuthentication() {   
        return new PasswordAuthentication(user, password);   
    }   
  
    public synchronized void sendMail(String subject, String body, String sender, String recipients) throws Exception {   
        try{
        MimeMessage message = new MimeMessage(session);   
        DataHandler handler = new DataHandler(new ByteArrayDataSource(body.getBytes(), "text/plain"));   
        message.setSender(new InternetAddress(sender));   
        message.setSubject(subject);   
        message.setDataHandler(handler);   
        if (recipients.indexOf(',') > 0)   
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipients));   
        else  
            message.setRecipient(Message.RecipientType.TO, new InternetAddress(recipients));   
        Transport.send(message);   
        }catch(Exception e){
            
        }
    }   
  
    public class ByteArrayDataSource implements DataSource {   
        private byte[] data;   
        private String type;   
  
        public ByteArrayDataSource(byte[] data, String type) {   
            super();   
            this.data = data;   
            this.type = type;   
        }   
  
        public ByteArrayDataSource(byte[] data) {   
            super();   
            this.data = data;   
        }   
  
        public void setType(String type) {   
            this.type = type;   
        }   
  
        public String getContentType() {   
            if (type == null)   
                return "application/octet-stream";   
            else  
                return type;   
        }   
  
        public InputStream getInputStream() throws IOException {   
            return new ByteArrayInputStream(data);   
        }   
  
        public String getName() {   
            return "ByteArrayDataSource";   
        }   
  
        public OutputStream getOutputStream() throws IOException {   
            throw new IOException("Not Supported");   
        }   
    }   
}  

JSSEProvider.java:

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/**
 * @author Alexander Y. Kleymenov
 * @version $Revision$
 */


import java.security.AccessController;
import java.security.Provider;

public final class JSSEProvider extends Provider {

    public JSSEProvider() {
        super("HarmonyJSSE", 1.0, "Harmony JSSE Provider");
        AccessController.doPrivileged(new java.security.PrivilegedAction<Void>() {
            public Void run() {
                put("SSLContext.TLS",
                        "org.apache.harmony.xnet.provider.jsse.SSLContextImpl");
                put("Alg.Alias.SSLContext.TLSv1", "TLS");
                put("KeyManagerFactory.X509",
                        "org.apache.harmony.xnet.provider.jsse.KeyManagerFactoryImpl");
                put("TrustManagerFactory.X509",
                        "org.apache.harmony.xnet.provider.jsse.TrustManagerFactoryImpl");
                return null;
            }
        });
    }
}

将下面链接中的3个罐子添加到你的Android项目中

mail.jar activation.jar additional.jar

点击这里-如何添加外部罐子

别忘了在你的清单上加上这一行:

<uses-permission android:name="android.permission.INTERNET" />

只需点击下面的链接，更改帐户访问不太安全的应用程序 https://www.google.com/settings/security/lesssecureapps

运行项目并检查收件人邮件帐户。

另外，别忘了你不能在android的任何活动中进行网络操作。 因此，建议使用AsyncTask或IntentService来避免主线程网络异常。

Jar文件:https://code.google.com/archive/p/javamail-android/