E-Mails senden

Es gibt zwei Möglichkeiten, E-Mails über die Gmail API zu senden:

• Sie können sie direkt mit der Methode messages.send senden.
• Sie können sie mit der Methode drafts.send aus einem Entwurf senden.

E-Mails werden als Base64url-codierte Strings im Attribut raw einer Nachrichtenressource gesendet. Der übergeordnete Workflow zum Senden einer E-Mail sieht so aus:

1. Erstellen Sie die E-Mail-Inhalte auf bequeme Weise und codieren Sie sie als base64-URL-String.
2. Erstellen Sie eine neue Nachrichtenressource und legen Sie ihre raw-Property auf den gerade erstellten base64url-String fest.
3. Rufen Sie messages.send auf. Wenn Sie einen Entwurf senden, drafts.send, um die Nachricht zu senden.

Die Details dieses Workflows können je nach Auswahl der Clientbibliothek und der Programmiersprache variieren.

Nachrichten erstellen

Die Gmail API erfordert MIME-E-Mail-Nachrichten, die RFC 2822-konform sind und als base64url-Strings codiert sind. Viele Programmiersprachen haben Bibliotheken oder Dienstprogramme, die das Erstellen und Codieren von MIME-Nachrichten vereinfachen. Die folgenden Codebeispiele zeigen, wie Sie mithilfe der Google APIs-Clientbibliotheken für verschiedene Sprachen eine MIME-Nachricht erstellen.

Java

Das Erstellen einer E-Mail-Nachricht kann durch die MimeMessage-Klasse im Paket javax.mail.internet erheblich vereinfacht werden. Das folgende Beispiel zeigt, wie Sie die E-Mail-Nachricht einschließlich der Header erstellen:

gmail/snippets/src/main/java/CreateEmail.java

Auf GitHub ansehen

import java.util.Properties;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

/* Class to demonstrate the use of Gmail Create Email API  */
public class CreateEmail {

  /**
   * Create a MimeMessage using the parameters provided.
   *
   * @param toEmailAddress   email address of the receiver
   * @param fromEmailAddress email address of the sender, the mailbox account
   * @param subject          subject of the email
   * @param bodyText         body text of the email
   * @return the MimeMessage to be used to send email
   * @throws MessagingException - if a wrongly formatted address is encountered.
   */
  public static MimeMessage createEmail(String toEmailAddress,
                                        String fromEmailAddress,
                                        String subject,
                                        String bodyText)
      throws MessagingException {
    Properties props = new Properties();
    Session session = Session.getDefaultInstance(props, null);

    MimeMessage email = new MimeMessage(session);

    email.setFrom(new InternetAddress(fromEmailAddress));
    email.addRecipient(javax.mail.Message.RecipientType.TO,
        new InternetAddress(toEmailAddress));
    email.setSubject(subject);
    email.setText(bodyText);
    return email;
  }
}

Im nächsten Schritt wird das MimeMessage codiert, ein Message-Objekt instanziiert und der base64url-codierte Nachrichtenstring als Wert des Attributs raw festgelegt.

gmail/snippets/src/main/java/CreateMessage.java

Auf GitHub ansehen

import com.google.api.services.gmail.model.Message;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import org.apache.commons.codec.binary.Base64;

/* Class to demonstrate the use of Gmail Create Message API */
public class CreateMessage {

  /**
   * Create a message from an email.
   *
   * @param emailContent Email to be set to raw of message
   * @return a message containing a base64url encoded email
   * @throws IOException        - if service account credentials file not found.
   * @throws MessagingException - if a wrongly formatted address is encountered.
   */
  public static Message createMessageWithEmail(MimeMessage emailContent)
      throws MessagingException, IOException {
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    emailContent.writeTo(buffer);
    byte[] bytes = buffer.toByteArray();
    String encodedEmail = Base64.encodeBase64URLSafeString(bytes);
    Message message = new Message();
    message.setRaw(encodedEmail);
    return message;
  }
}

Python

Das folgende Codebeispiel zeigt, wie eine MIME-Nachricht erstellt, in einen base64url-String codiert und dem Feld raw der Ressource Message zugewiesen wird:

gmail/snippet/send mail/create_entwurf.py

Auf GitHub ansehen

from __future__ import print_function

import base64
from email.message import EmailMessage

import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError


def gmail_create_draft():
    """Create and insert a draft email.
       Print the returned draft's message and id.
       Returns: Draft object, including draft id and message meta data.

      Load pre-authorized user credentials from the environment.
      TODO(developer) - See https://developers.google.com/identity
      for guides on implementing OAuth2 for the application.
    """
    creds, _ = google.auth.default()

    try:
        # create gmail api client
        service = build('gmail', 'v1', credentials=creds)

        message = EmailMessage()

        message.set_content('This is automated draft mail')

        message['To'] = '[e-mail]'
        message['From'] = '[e-mail]'
        message['Subject'] = 'Automated draft'

        # encoded message
        encoded_message = base64.urlsafe_b64encode(message.as_bytes()).decode()

        create_message = {
            'message': {
                'raw': encoded_message
            }
        }
        # pylint: disable=E1101
        draft = service.users().drafts().create(userId="me",
                                                body=create_message).execute()

        print(F'Draft id: {draft["id"]}\nDraft message: {draft["message"]}')

    except HttpError as error:
        print(F'An error occurred: {error}')
        draft = None

    return draft


if __name__ == '__main__':
    gmail_create_draft()

Nachrichten mit Anhängen erstellen

Das Erstellen einer Nachricht mit einem Anhang ist mit dem Erstellen einer anderen Nachricht vergleichbar. Der Vorgang zum Hochladen der Datei als mehrteilige MIME-Nachricht hängt jedoch von der Programmiersprache ab. Die folgenden Codebeispiele zeigen mögliche Möglichkeiten, eine mehrteilige MIME-Nachricht mit einem Anhang zu erstellen.

Java

Das folgende Beispiel zeigt, wie Sie eine mehrteilige MIME-Nachricht erstellen. Die Codierung und die Zuweisungsschritte sind mit denen oben identisch.

gmail/snippets/src/main/java/CreateDraftWithAttachment.java

Auf GitHub ansehen

import com.google.api.client.googleapis.json.GoogleJsonError;
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.GmailScopes;
import com.google.api.services.gmail.model.Draft;
import com.google.api.services.gmail.model.Message;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.util.Properties;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import org.apache.commons.codec.binary.Base64;

/* Class to demonstrate the use of Gmail Create Draft with attachment API */
public class CreateDraftWithAttachment {
  /**
   * Create a draft email with attachment.
   *
   * @param fromEmailAddress - Email address to appear in the from: header.
   * @param toEmailAddress   - Email address of the recipient.
   * @param file             - Path to the file to be attached.
   * @return the created draft, {@code null} otherwise.
   * @throws MessagingException - if a wrongly formatted address is encountered.
   * @throws IOException        - if service account credentials file not found.
   */
  public static Draft createDraftMessageWithAttachment(String fromEmailAddress,
                                                       String toEmailAddress,
                                                       File file)
      throws MessagingException, IOException {
        /* Load pre-authorized user credentials from the environment.
         TODO(developer) - See https://developers.google.com/identity for
          guides on implementing OAuth2 for your application.*/
    GoogleCredentials credentials = GoogleCredentials.getApplicationDefault()
        .createScoped(GmailScopes.GMAIL_COMPOSE);
    HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(credentials);

    // Create the gmail API client
    Gmail service = new Gmail.Builder(new NetHttpTransport(),
        GsonFactory.getDefaultInstance(),
        requestInitializer)
        .setApplicationName("Gmail samples")
        .build();

    // Create the email content
    String messageSubject = "Test message";
    String bodyText = "lorem ipsum.";

    // Encode as MIME message
    Properties props = new Properties();
    Session session = Session.getDefaultInstance(props, null);
    MimeMessage email = new MimeMessage(session);
    email.setFrom(new InternetAddress(fromEmailAddress));
    email.addRecipient(javax.mail.Message.RecipientType.TO,
        new InternetAddress(toEmailAddress));
    email.setSubject(messageSubject);

    MimeBodyPart mimeBodyPart = new MimeBodyPart();
    mimeBodyPart.setContent(bodyText, "text/plain");
    Multipart multipart = new MimeMultipart();
    multipart.addBodyPart(mimeBodyPart);
    mimeBodyPart = new MimeBodyPart();
    DataSource source = new FileDataSource(file);
    mimeBodyPart.setDataHandler(new DataHandler(source));
    mimeBodyPart.setFileName(file.getName());
    multipart.addBodyPart(mimeBodyPart);
    email.setContent(multipart);

    // Encode and wrap the MIME message into a gmail message
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    email.writeTo(buffer);
    byte[] rawMessageBytes = buffer.toByteArray();
    String encodedEmail = Base64.encodeBase64URLSafeString(rawMessageBytes);
    Message message = new Message();
    message.setRaw(encodedEmail);

    try {
      // Create the draft message
      Draft draft = new Draft();
      draft.setMessage(message);
      draft = service.users().drafts().create("me", draft).execute();
      System.out.println("Draft id: " + draft.getId());
      System.out.println(draft.toPrettyString());
      return draft;
    } catch (GoogleJsonResponseException e) {
      // TODO(developer) - handle error appropriately
      GoogleJsonError error = e.getDetails();
      if (error.getCode() == 403) {
        System.err.println("Unable to create draft: " + e.getDetails());
      } else {
        throw e;
      }
    }
    return null;
  }
}

Python

Ähnlich wie im vorherigen Beispiel wird in diesem Beispiel die Nachricht in base64url codiert und dem Feld raw der Ressource Message zugewiesen.

gmail/snippet/send mail/create_draft_with_attachment.py

Auf GitHub ansehen

from __future__ import print_function

import base64
import mimetypes
import os
from email.message import EmailMessage
from email.mime.audio import MIMEAudio
from email.mime.base import MIMEBase
from email.mime.image import MIMEImage
from email.mime.text import MIMEText

import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError


def gmail_create_draft_with_attachment():
    """Create and insert a draft email with attachment.
       Print the returned draft's message and id.
      Returns: Draft object, including draft id and message meta data.

      Load pre-authorized user credentials from the environment.
      TODO(developer) - See https://developers.google.com/identity
      for guides on implementing OAuth2 for the application.
    """
    creds, _ = google.auth.default()

    try:
        # create gmail api client
        service = build('gmail', 'v1', credentials=creds)
        mime_message = EmailMessage()

        # headers
        mime_message['To'] = '[e-mail]'
        mime_message['From'] = '[e-mail]'
        mime_message['Subject'] = 'sample with attachment'

        # text
        mime_message.set_content(
            'Hi, this is automated mail with attachment.'
            'Please do not reply.'
        )

        # attachment
        attachment_filename = 'photo.jpg'
        # guessing the MIME type
        type_subtype, _ = mimetypes.guess_type(attachment_filename)
        maintype, subtype = type_subtype.split('/')

        with open(attachment_filename, 'rb') as fp:
            attachment_data = fp.read()
        mime_message.add_attachment(attachment_data, maintype, subtype)

        encoded_message = base64.urlsafe_b64encode(mime_message.as_bytes()).decode()

        create_draft_request_body = {
            'message': {
                'raw': encoded_message
            }
        }
        # pylint: disable=E1101
        draft = service.users().drafts().create(userId="me",
                                                body=create_draft_request_body)\
            .execute()
        print(F'Draft id: {draft["id"]}\nDraft message: {draft["message"]}')
    except HttpError as error:
        print(F'An error occurred: {error}')
        draft = None
    return draft


def build_file_part(file):
    """Creates a MIME part for a file.

    Args:
      file: The path to the file to be attached.

    Returns:
      A MIME part that can be attached to a message.
    """
    content_type, encoding = mimetypes.guess_type(file)

    if content_type is None or encoding is not None:
        content_type = 'application/octet-stream'
    main_type, sub_type = content_type.split('/', 1)
    if main_type == 'text':
        with open(file, 'rb'):
            msg = MIMEText('r', _subtype=sub_type)
    elif main_type == 'image':
        with open(file, 'rb'):
            msg = MIMEImage('r', _subtype=sub_type)
    elif main_type == 'audio':
        with open(file, 'rb'):
            msg = MIMEAudio('r', _subtype=sub_type)
    else:
        with open(file, 'rb'):
            msg = MIMEBase(main_type, sub_type)
            msg.set_payload(file.read())
    filename = os.path.basename(file)
    msg.add_header('Content-Disposition', 'attachment', filename=filename)
    return msg


if __name__ == '__main__':
    gmail_create_draft_with_attachment()

Nachrichten werden gesendet

Nachdem Sie eine Nachricht erstellt haben, können Sie sie senden, indem Sie sie wie im folgenden Beispiel gezeigt im Anfragetext eines Aufrufs von messages.send angeben.

Java

gmail/snippets/src/main/java/SendMessage.java

Auf GitHub ansehen

import com.google.api.client.googleapis.json.GoogleJsonError;
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.GmailScopes;
import com.google.api.services.gmail.model.Message;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Properties;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import org.apache.commons.codec.binary.Base64;

/* Class to demonstrate the use of Gmail Send Message API */
public class SendMessage {
  /**
   * Send an email from the user's mailbox to its recipient.
   *
   * @param fromEmailAddress - Email address to appear in the from: header
   * @param toEmailAddress   - Email address of the recipient
   * @return the sent message, {@code null} otherwise.
   * @throws MessagingException - if a wrongly formatted address is encountered.
   * @throws IOException        - if service account credentials file not found.
   */
  public static Message sendEmail(String fromEmailAddress,
                                  String toEmailAddress)
      throws MessagingException, IOException {
        /* Load pre-authorized user credentials from the environment.
           TODO(developer) - See https://developers.google.com/identity for
            guides on implementing OAuth2 for your application.*/
    GoogleCredentials credentials = GoogleCredentials.getApplicationDefault()
        .createScoped(GmailScopes.GMAIL_SEND);
    HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(credentials);

    // Create the gmail API client
    Gmail service = new Gmail.Builder(new NetHttpTransport(),
        GsonFactory.getDefaultInstance(),
        requestInitializer)
        .setApplicationName("Gmail samples")
        .build();

    // Create the email content
    String messageSubject = "Test message";
    String bodyText = "lorem ipsum.";

    // Encode as MIME message
    Properties props = new Properties();
    Session session = Session.getDefaultInstance(props, null);
    MimeMessage email = new MimeMessage(session);
    email.setFrom(new InternetAddress(fromEmailAddress));
    email.addRecipient(javax.mail.Message.RecipientType.TO,
        new InternetAddress(toEmailAddress));
    email.setSubject(messageSubject);
    email.setText(bodyText);

    // Encode and wrap the MIME message into a gmail message
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    email.writeTo(buffer);
    byte[] rawMessageBytes = buffer.toByteArray();
    String encodedEmail = Base64.encodeBase64URLSafeString(rawMessageBytes);
    Message message = new Message();
    message.setRaw(encodedEmail);

    try {
      // Create send message
      message = service.users().messages().send("me", message).execute();
      System.out.println("Message id: " + message.getId());
      System.out.println(message.toPrettyString());
      return message;
    } catch (GoogleJsonResponseException e) {
      // TODO(developer) - handle error appropriately
      GoogleJsonError error = e.getDetails();
      if (error.getCode() == 403) {
        System.err.println("Unable to send message: " + e.getDetails());
      } else {
        throw e;
      }
    }
    return null;
  }
}

Python

gmail/snippet/send mail/send_message.py

Auf GitHub ansehen

from __future__ import print_function

import base64
from email.message import EmailMessage

import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError


def gmail_send_message():
    """Create and send an email message
    Print the returned  message id
    Returns: Message object, including message id

    Load pre-authorized user credentials from the environment.
    TODO(developer) - See https://developers.google.com/identity
    for guides on implementing OAuth2 for the application.
    """
    creds, _ = google.auth.default()

    try:
        service = build('gmail', 'v1', credentials=creds)
        message = EmailMessage()

        message.set_content('This is automated draft mail')

        message['To'] = '[e-mail]'
        message['From'] = '[e-mail]'
        message['Subject'] = 'Automated draft'

        # encoded message
        encoded_message = base64.urlsafe_b64encode(message.as_bytes()) \
            .decode()

        create_message = {
            'raw': encoded_message
        }
        # pylint: disable=E1101
        send_message = (service.users().messages().send
                        (userId="me", body=create_message).execute())
        print(F'Message Id: {send_message["id"]}')
    except HttpError as error:
        print(F'An error occurred: {error}')
        send_message = None
    return send_message


if __name__ == '__main__':
    gmail_send_message()

Wenn Sie eine Antwort senden und die E-Mail in einen Thread einfügen möchten, achten Sie auf Folgendes:

1. Die Subject-Header stimmen überein
2. Die Header References und In-Reply-To folgen dem RFC 2822-Standard.

Informationen zum Senden einer Nachricht aus einem Entwurf finden Sie unter Entwürfe erstellen.