diff --git a/src/mailMerge.gs b/src/mailMerge.gs
new file mode 100644
index 0000000..18cb81d
--- /dev/null
+++ b/src/mailMerge.gs
@@ -0,0 +1,196 @@
+// Add spreadsheet menu
+function onOpen() {
+  let ui = SpreadsheetApp.getUi();
+  ui.createMenu('Mail Merge')
+    .addItem('Send Emails', 'sendEmails')
+    .addSeparator()
+    .addItem('Create Draft', 'createDraftEmails')
+    .addToUi();
+}
+
+/**
+ * Send personalized email(s) to recipient address listed in sheet 'SHEET_NAME_DATA'
+ */
+function sendEmails() {
+  const draftMode = false;
+  const config = getConfig_('Config');
+  sendPersonalizedEmails_(draftMode, config);
+}
+
+/**
+ * Send test emails to myself the content of the first row in sheet 'List'
+ */
+function createDraftEmails() {
+  const draftMode = true;
+  const config = getConfig_('Config');
+  sendPersonalizedEmails_(draftMode, config);
+}
+
+/**
+ * Bulk send personalized emails based on a designated Gmail draft.
+ * The email(s) can be sent to multiple recipients, which will serve as an alternative for using BCC.
+ * @param {boolean} draftMode Creates Gmail draft(s) instead of sending email. Defaults to true.
+ * @param {Object} config Object returned by getConfig_()
+ */
+function sendPersonalizedEmails_(draftMode = true, config) {
+  var ss = SpreadsheetApp.getActiveSpreadsheet();
+  var ui = SpreadsheetApp.getUi();
+  var myEmail = Session.getActiveUser().getEmail();
+
+  // Get data of field(s) to merge
+  //// Range of data
+  const dataSheet = ss.getSheetByName(config.DATA_SHEET_NAME);
+  var mergeDataRange = dataSheet.getDataRange().setNumberFormat('@'); // Convert all formatted dates and numbers into texts
+  //// Get data
+  var mergeData = mergeDataRange.getValues();
+  //// Define first row of mergeData as header
+  var header = mergeData.shift();
+  //// Convert 2d array of mergeData into object array
+  var mergeDataObj = mergeData.map(function (values) {
+    return header.reduce(function (object, key, index) {
+      object[key] = values[index];
+      return object;
+    }, {});
+  })
+
+  try {
+    // Confirmation before sending email
+    let confirmAccount = (draftMode === true
+      ? `Are you sure you want to create draft email(s) as ${myEmail}?`
+      : `Are you sure you want to send email(s) as ${myEmail}?`);
+    let answer = ui.alert(confirmAccount, ui.ButtonSet.OK_CANCEL);
+    if (answer !== ui.Button.OK) {
+      throw new Error('Canceled.');
+    }
+
+    // Email Template
+    //// Prompt to enter the subject of the Gmail draft to use as template
+    let promptMessage = 'Enter the subject text of Gmail draft to use as template.';
+    let promptResult = ui.prompt(promptMessage, ui.ButtonSet.OK_CANCEL);
+    let [selectedButton, subjectText] = [promptResult.getSelectedButton(), promptResult.getResponseText()];
+    if (selectedButton !== ui.Button.OK) {
+      throw new Error('Canceled.');
+    } else if (subjectText == null) {
+      throw new Error('No text entered.');
+    }
+    //// Get template
+    let draftMessage = getDraftBySubject_(subjectText);
+    if (draftMessage.length > 1) {
+      throw new Error('There are 2 or more Gmail drafts with the subject you entered. Enter a unique subject text.');
+    }
+    var template = {
+      'subject': subjectText,
+      'plainBody': draftMessage[0].getPlainBody(),
+      'htmlBody': draftMessage[0].getBody()
+    };
+
+    // Send or create draft of personalized email
+    mergeDataObj.forEach((element, i) => {
+      var messageData = fillInTemplateFromObject_(template, element, config.MERGE_FIELD_MARKER, config.REPLACE_VALUE);
+      var options = {
+        'htmlBody': messageData.htmlBody,
+        'bcc': (config.BCC_TO_MYSELF === true ? myEmail : null)
+      };
+      draftMode === true
+        ? GmailApp.createDraft(element[config.RECIPIENT_COL_NAME], messageData.subject, messageData.plainBody, options)
+        : GmailApp.sendEmail(element[config.RECIPIENT_COL_NAME], messageData.subject, messageData.plainBody, options);
+    });
+    let completeMessage = (draftMode === true
+      ? 'Complete: All draft(s) created.'
+      : 'Complete: All mails sent.');
+    ui.alert(completeMessage)
+  } catch (e) {
+    let message = errorMessage_(e);
+    ui.alert(message);
+  }
+}
+
+/**
+ * Returns an object of configurations from spreadsheet.
+ * The sheet should have a first row of headers, and its first column should include the following properties:
+ * DATA_SHEET_NAME: {string} Name of sheet in which field(s) to merge in email are stored
+ * RECIPIENT_COL_NAME: {string} Name of column in sheet 'DATA_SHEET_NAME' that designates the email address of the recipient
+ * BCC_TO_MYSELF: {string} String boolean. When true, will send (or create draft) email with the sender's address set to BCC.
+ * REPLACE_VALUE: {string} Text that will replace empty data of marker. 
+ * MERGE_FIELD_MARKER: {string} Text to be processed in RegExp() constructor to define merge field marker. Note that the backslash itself does not need to be escaped, i.e., does not need to be repeated.
+ * 
+ * @param {string} configSheetName Name of sheet with configurations. Defaults to 'Config'.
+ * @return {Object}
+ */
+function getConfig_(configSheetName = 'Config') {
+  // Get values from spreadsheet
+  let configValues = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(configSheetName).getDataRange().getValues();
+  configValues.shift();
+
+  // Convert the 2d array values into a Javascript object
+  let configObj = {};
+  configValues.forEach(element => configObj[element[0]] = element[1]);
+
+  // Convert data types
+  configObj.BCC_TO_MYSELF = toBoolean_(configObj.BCC_TO_MYSELF);
+  configObj.MERGE_FIELD_MARKER = new RegExp(configObj.MERGE_FIELD_MARKER, 'g');
+
+  return configObj;
+}
+
+/**
+ * Convert string booleans into boolean data
+ * @param {string} stringBoolean 
+ * @return {boolean}
+ */
+function toBoolean_(stringBoolean) {
+  return stringBoolean.toLowerCase === 'true';
+}
+
+/**
+ * Get an array of Gmail message(s) with the designated subject
+ * @param {string} subject Subject text of Gmail draft
+ * @return {array} Array of GmailMessage class objects. https://developers.google.com/apps-script/reference/gmail/gmail-message
+ */
+function getDraftBySubject_(subject) {
+  let draftMessages = GmailApp.getDraftMessages();
+  let targetDrafts = draftMessages.filter(element => element.getSubject() == subject);
+  return targetDrafts;
+}
+
+/**
+ * Replaces markers in a template object with values defined in a JavaScript data object.
+ * @param {Object} template Template object containing markers, as designated in regular expression in MERGE_FIELD_MARKER
+ * @param {Object} mergeData Object with values to replace markers.
+ * @param {string} mergeFieldMarker Regular expression for the merge field marker. Defaults to /\{\{[^\}]+\}\}/g e.g., {{field name}}
+ * @param {string} replaceValue String to replace empty data of a marker. Defaults to 'NA' for Not Available. 
+ * @return {Object} Returns object with markers replaced.
+ */
+function fillInTemplateFromObject_(template, mergeData, mergeFieldMarker = /\{\{[^\}]+\}\}/g, replaceValue = 'NA') {
+  let messageData = {};
+  for (let k in template) {
+    let text = '';
+    text = template[k];
+    // Search for all the variables to be replaced
+    let textVars = text.match(mergeFieldMarker);
+    if (!textVars) {
+      messageData[k] = text; // return text itself if no marker is found
+    } else {
+      // Get the text inside markers. e.g., {{field name}} => field name
+      // assuming that the text length for opening and closing markers are 2 and 2, respectively 
+      let markerText = textVars.map(value => value.substring(2, value.length - 2));
+      // Replace variables in textVars with the actual values from the data object.
+      // If no value is available, replace with the string with replaceValue.
+      textVars.forEach(
+        (variable, i) => text = text.replace(variable, mergeData[markerText[i]] || replaceValue)
+      );
+      messageData[k] = text;
+    }
+  }
+  return messageData;
+}
+
+/**
+ * Standarized error message
+ * @param {Object} e Error object returned by try-catch
+ * @return {string} Standarized error message
+ */
+function errorMessage_(e) {
+  let message = `Error: line - ${e.lineNumber}\n[${e.name}] ${e.message}\n${e.stack}`
+  return message;
+}