Gmail Automation: The Complete Google Apps Script Guide (2025)

 1function autoReply() {
 2  // Get the current thread.
 3  let thread = GmailApp.currentThread()
 4  // Get the sender's email address.
 5  const sender = thread.getMessage(0).getFrom()
 6
 7  // Check if the sender is already in the 'Replied To' list.
 8  const labels = thread.getLabels()
 9  if (labels.some(label => label.getName() === 'Replied To')) {
10    return // Skip if already replied
11  }
12
13  const importantResponse = `
14    Thanks for your email!
15    I'm currently out of the office, but I'll get back to you as soon as I can.
16    In the meantime, please contact my colleague at colleague@example.com.`
17  const defaultResponse = `
18    Thanks for your email!
19    I'm currently out of the office and will respond upon my return.`
20
21  // Personalized responses.
22  var responses = {
23    "importantclient@example.com": importantResponse,
24    "default": defaultResponse
25  }
26
27  var replyMessage = responses[sender] || responses["default"]
28
29  // Send the personalized reply.
30  thread.reply(replyMessage)
31  // Add a label to avoid duplicate replies
32  thread.addLabel(GmailApp.createLabel('Replied To'))
33}

 1function summarizeLongEmailsUsingOpenAI() {
 2  const apiKey = "your-openai-api-key" // Replace with your OpenAI API key
 3  const threads = GmailApp.search("is:unread")
 4
 5  threads.forEach(thread => {
 6    const message = thread.getMessages()[0]
 7    const emailBody = message.getPlainBody()
 8
 9    // OpenAI API URL
10    const openAiUrl = "https://api.openai.com/v1/completions"
11
12    // Request payload
13    const payload = {
14      model: "gpt-4o-mini",
15      prompt: `Summarize the following email:\n\n${emailBody}\n\nSummary:`,
16      temperature: 0.5
17    }
18
19    // Set up the API request
20    const options = {
21      method: "post",
22      contentType: "application/json",
23      payload: JSON.stringify(payload),
24      headers: {
25        Authorization: `Bearer ${apiKey}`
26      }
27    }
28
29    // Make the API request
30    try {
31      const response = UrlFetchApp.fetch(openAiUrl, options)
32      const jsonResponse = JSON.parse(response.getContentText())
33      const summary = jsonResponse.choices[0].text.trim()
34
35      // Reply to the thread but only send to yourself
36      thread.replyAll(
37        `Summary of the email:\n\n${summary}\n\n---\nAutomatically generated by AI`,
38        {
39          to: Session.getActiveUser().getEmail(), // Only send to yourself
40          noReply: true  // Don't include original recipients
41        }
42      )
43
44      message.markRead()
45
46      // Add a label to track summarized emails
47      const summaryLabel = GmailApp.createLabel('AI-Summarized')
48      thread.addLabel(summaryLabel)
49    } catch (error) {
50      Logger.log("Error summarizing email: " + error)
51    }
52  })
53}

 1function logComplaintsToCRM() {
 2  const crmApiUrl = "https://api.crm.com/complaints"
 3  const threads = GmailApp.search("label:complaints")
 4
 5  threads.forEach(thread => {
 6    const message = thread.getMessages()[0]
 7    const payload = {
 8      customer: message.getFrom(),
 9      subject: message.getSubject(),
10      complaint: message.getPlainBody()
11    }
12
13    UrlFetchApp.fetch(crmApiUrl, {
14      method: "post",
15      contentType: "application/json",
16      payload: JSON.stringify(payload),
17      headers: { Authorization: `Bearer your-crm-api-key` }
18    })
19  })
20}

 1function autoCreateCalendarEvents() {
 2  const threads = GmailApp.search("subject:(meeting OR schedule)")
 3  const calendar = CalendarApp.getDefaultCalendar()
 4
 5  threads.forEach(thread => {
 6    const message = thread.getMessages()[0]
 7    const body = message.getPlainBody()
 8    const timeMatch = body.match(/\d{4}-\d{2}-\d{2} \d{2}:\d{2}/) // Example: 2025-01-15 14:00
 9
10    if (timeMatch) {
11      const eventDate = new Date(timeMatch[0])
12      calendar.createEvent(message.getSubject(), eventDate, new Date(eventDate.getTime() + 60 * 60 * 1000)) // 1-hour event
13    }
14  })
15}

 1function sendFollowUpReminders() {
 2  const labelName = "Follow-Up"
 3  const threads = GmailApp.getUserLabelByName(labelName).getThreads()
 4
 5  threads.forEach(thread => {
 6    const messages = thread.getMessages()
 7    const lastMessage = messages[messages.length - 1]
 8    if (!lastMessage.isInInbox()) {
 9      GmailApp.sendEmail(thread.getFirstMessageSubject(), "Follow-Up Reminder")
10    }
11  })
12}

 1function resendUnansweredEmails() {
 2  const threads = GmailApp.search("label:sent newer_than:7d")
 3
 4  threads.forEach(thread => {
 5    const messages = thread.getMessages()
 6    const lastMessage = messages[messages.length - 1]
 7    if (lastMessage.isDraft() && !thread.hasStarredMessages()) {
 8      GmailApp.sendEmail(thread.getFirstMessageSubject(), lastMessage.getBody())
 9    }
10  })
11}

 1function notifySlackForImportantEmails() {
 2  const slackWebhookUrl = "https://hooks.slack.com/services/your/slack/webhook"
 3  const threads = GmailApp.search("label:important is:unread")
 4
 5  threads.forEach(thread => {
 6    const message = thread.getMessages()[0]
 7    const payload = {
 8      text: `New Important Email: ${message.getSubject()} from ${message.getFrom()}`
 9    }
10    UrlFetchApp.fetch(slackWebhookUrl, {
11      method: "post",
12      contentType: "application/json",
13      payload: JSON.stringify(payload)
14    })
15  })
16}

 1function forwardEmails() {
 2  const recipient = "assistant@example.com"
 3  const threads = GmailApp.search("label:important")
 4
 5  threads.forEach(thread => {
 6    const messages = thread.getMessages()
 7    messages.forEach(message => {
 8      GmailApp.sendEmail(recipient, message.getSubject(), message.getPlainBody())
 9    })
10  })
11}

 1function organizeAttachmentsByCategory() {
 2  const categories = ["Invoices", "Reports", "Contracts"]
 3  const parentFolderId = "your-parent-folder-id-in-google-drive"
 4
 5  // Ensure all category folders exist and get their IDs
 6  const folderIds = {}
 7  categories.forEach(category => {
 8    folderIds[category] = getOrCreateFolder(category, parentFolderId)
 9  })
10
11  // Process Gmail threads with attachments
12  const threads = GmailApp.search("has:attachment")
13  threads.forEach(thread => {
14    const message = thread.getMessages()[0]
15    const subject = message.getSubject()
16    const attachments = message.getAttachments()
17
18    // Match email subject to a category and move attachments
19    for (const category in folderIds) {
20      if (subject.includes(category)) {
21        const folder = DriveApp.getFolderById(folderIds[category])
22        attachments.forEach(attachment => folder.createFile(attachment))
23      }
24    }
25  })
26}
27
28// Helper function to get or create a folder by name under a parent folder
29function getOrCreateFolder(folderName, parentFolderId) {
30  const parentFolder = DriveApp.getFolderById(parentFolderId)
31  const folders = parentFolder.getFoldersByName(folderName)
32
33  // If the folder already exists, return its ID
34  if (folders.hasNext()) {
35    return folders.next().getId()
36  }
37
38  // Otherwise, create the folder and return the new ID
39  const newFolder = parentFolder.createFolder(folderName)
40  return newFolder.getId()
41}