Class GmailMessage

// Create a draft reply to the original message with an acknowledgment.
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.createDraftReply("Got your message");

// Create a draft response with an HTML text body.
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.createDraftReply("incapable of HTML", {
  htmlBody: "<b>some HTML body text</b>",
  cc: "another@example.com"
});

// Create a draft response to all recipients (except those bcc'd) with an acknowledgment.
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.createDraftReplyAll("Got your message");

// Create a draft response to all recipients (except those bcc'd) using an HTML text body.
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.createDraftReplyAll("incapable of HTML", {
  htmlBody: "<b>some HTML body text</b>",
  cc: "another@example.com"
});

// Forward first message of first inbox thread to recipient1 & recipient2, both @example.com
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.forward("recipient1@example.com,recipient2@example.com");

var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.forward("recipient1@example.com,recipient2@example.com", {
  cc: "myboss@example.com",
  bcc: "mybosses-boss@example.com,vp@example.com"
});

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getBcc()); // Log bcc'd addresses

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getBody()); // Log contents of the body

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getCc()); // Log cc'd addresses

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getDate()); // Log date and time of the message

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getFrom()); // Log from address of the message

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox.
var message = thread.getMessages()[0];         // Get the first message.
Logger.log(message.getHeader("Message-ID"));   // Logs the Message-ID RFC 2822 header.

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
var id = message.getId();
var messageById = GmailApp.getMessageById(id);
Logger.log(message.getSubject() == messageById.getMessage()); // Always logs true

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getPlainBody()); // Log contents of the body

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getReplyTo()); // Logs reply-to address

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getSubject()); // Log subject line

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getThread().getFirstMessageSubject() ==
           thread.getFirstMessageSubject()); // Always logs true

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log(message.getTo()); // Log the recipient of message

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log("is draft? " + message.isDraft());

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log("is a chat? " + message.isInChats());

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log("is in inbox? " + message.isInInbox());

var thread = GmailApp.getPriorityInboxThreads(0,1)[0]; // Get first thread in priority inbox
var messages = thread.getMessages();
for (var i = 0; i < messages.length; i++) {
  // At least one of the messages is in priority inbox
  Logger.log("is in priority inbox? " + messages[i].isInPriorityInbox());
}

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log("is in the trash? " + message.isInTrash());

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log("is starred? " + message.isStarred());

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
Logger.log("is unread? " + message.isUnread());

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
message.markRead(); // Mark as read

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
message.markUnread(); // Mark as unread

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
message.moveToTrash(); // Move message to trash

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
// .. Do bunch of stuff here
message.refresh(); // Make sure it's up to date
// Do more stuff to message

// Respond to author of message with acknowledgment
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.reply("Got your message");

// Respond with HTML body text
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.reply("incapable of HTML", {
  htmlBody: "<b>some HTML body text</b>",
  noReply: true
});

// Respond to all recipients (except bcc'd) of last email in thread with acknowledgment
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
message.replyAll("Got your message");

// Respond with HTML body text
var firstThread = GmailApp.getInboxThreads(0,1)[0];
var message = firstThread.getMessages()[0];
messageThread.replyAll("incapable of HTML", {
  htmlBody: "<b>some HTML body text</b>",
  noReply: true
});

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
message.star(); // Star the message

var thread = GmailApp.getInboxThreads(0,1)[0]; // Get first thread in inbox
var message = thread.getMessages()[0]; // Get first message
message.unstar(); // Unstar the message