Create a mail merge with Gmail & Google Sheets

// To learn how to use this script, refer to the documentation:
// https://developers.google.com/apps-script/samples/automations/mail-merge
/*
Copyright 2022 Martin Hawksey
Licensed 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
 https://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.
*/
/**
 * @OnlyCurrentDoc
 */
/**
 * Change these to match the column names you are using for email
 * recipient addresses and email sent column.
 */
constRECIPIENT_COL="Recipient";
constEMAIL_SENT_COL="Email Sent";
/**
 * Creates the menu item "Mail Merge" for user to run scripts on drop-down.
 */
functiononOpen(){
constui=SpreadsheetApp.getUi();
ui.createMenu("Mail Merge").addItem("Send Emails","sendEmails").addToUi();
}
/**
 * Sends emails from sheet data.
 * @param {string} subjectLine (optional) for the email draft message
 * @param {Sheet} sheet to read data from
 */
functionsendEmails(subjectLine,sheet=SpreadsheetApp.getActiveSheet()){
// option to skip browser prompt if you want to use this code in other projects
letprocessedSubjectLine=subjectLine;
if(!processedSubjectLine){
processedSubjectLine=Browser.inputBox(
"Mail Merge",
"Type or copy/paste the subject line of the Gmail "+
"draft message you would like to mail merge with:",
Browser.Buttons.OK_CANCEL,
);
if(processedSubjectLine==="cancel"||processedSubjectLine===""){
// If no subject line, finishes up
return;
}
}
// Gets the draft Gmail message to use as a template
constemailTemplate=getGmailTemplateFromDrafts_(processedSubjectLine);
// Gets the data from the passed sheet
constdataRange=sheet.getDataRange();
// Fetches displayed values for each row in the Range HT Andrew Roberts
// https://mashe.hawksey.info/2020/04/a-bulk-email-mail-merge-with-gmail-and-google-sheets-solution-evolution-using-v8/#comment-187490
// @see https://developers.google.com/apps-script/reference/spreadsheet/range#getdisplayvalues
constdata=dataRange.getDisplayValues();
// Assumes row 1 contains our column headings
constheads=data.shift();
// Gets the index of the column named 'Email Status' (Assumes header names are unique)
// @see http://ramblings.mcpher.com/Home/excelquirks/gooscript/arrayfunctions
constemailSentColIdx=heads.indexOf(EMAIL_SENT_COL);
// Converts 2d array into an object array
// See https://stackoverflow.com/a/22917499/1027723
// For a pretty version, see https://mashe.hawksey.info/?p=17869/#comment-184945
constobj=data.map((r)=>
heads.reduce((o,k,i)=>{
o[k]=r[i]||"";
returno;
},{}),
);
// Creates an array to record sent emails
constout=[];
// Loops through all the rows of data
obj.forEach((row,rowIdx)=>{
// Only sends emails if email_sent cell is blank and not hidden by a filter
if(row[EMAIL_SENT_COL]===""){
try{
constmsgObj=fillInTemplateFromObject_(emailTemplate.message,row);
// See https://developers.google.com/apps-script/reference/gmail/gmail-app#sendEmail(String,String,String,Object)
// If you need to send emails with unicode/emoji characters change GmailApp for MailApp
// Uncomment advanced parameters as needed (see docs for limitations)
GmailApp.sendEmail(row[RECIPIENT_COL],msgObj.subject,msgObj.text,{
htmlBody:msgObj.html,
// bcc: 'a.bcc@email.com',
// cc: 'a.cc@email.com',
// from: 'an.alias@email.com',
// name: 'name of the sender',
// replyTo: 'a.reply@email.com',
// noReply: true, // if the email should be sent from a generic no-reply email address (not available to gmail.com users)
attachments:emailTemplate.attachments,
inlineImages:emailTemplate.inlineImages,
});
// Edits cell to record email sent date
out.push([newDate()]);
}catch(e){
// modify cell to record error
out.push([e.message]);
}
}else{
out.push([row[EMAIL_SENT_COL]]);
}
});
// Updates the sheet with new data
sheet.getRange(2,emailSentColIdx+1,out.length).setValues(out);
/**
 * Get a Gmail draft message by matching the subject line.
 * @param {string} subject_line to search for draft message
 * @return {object} containing the subject, plain and html message body and attachments
 */
functiongetGmailTemplateFromDrafts_(subject_line){
try{
// get drafts
constdrafts=GmailApp.getDrafts();
// filter the drafts that match subject line
constdraft=drafts.filter(subjectFilter_(subject_line))[0];
// get the message object
constmsg=draft.getMessage();
// Handles inline images and attachments so they can be included in the merge
// Based on https://stackoverflow.com/a/65813881/1027723
// Gets all attachments and inline image attachments
constallInlineImages=draft.getMessage().getAttachments({
includeInlineImages:true,
includeAttachments:false,
});
constattachments=draft
.getMessage()
.getAttachments({includeInlineImages:false});
consthtmlBody=msg.getBody();
// Creates an inline image object with the image name as key
// (can't rely on image index as array based on insert order)
constimg_obj=allInlineImages.reduce((obj,i)=>{
obj[i.getName()]=i;
returnobj;
},{});
//Regexp searches for all img string positions with cid
constimgexp=/<img.*?src="cid:(.*?)".*?alt="(.*?)"[^\>]+>/g;
constmatches=[...htmlBody.matchAll(imgexp)];
//Initiates the allInlineImages object
constinlineImagesObj={};
for(constmatchofmatches){
inlineImagesObj[match[1]]=img_obj[match[2]];
}
return{
message:{
subject:subject_line,
text:msg.getPlainBody(),
html:htmlBody,
},
attachments:attachments,
inlineImages:inlineImagesObj,
};
}catch(e){
thrownewError("Oops - can't find Gmail draft");
}
/**
 * Filter draft objects with the matching subject linemessage by matching the subject line.
 * @param {string} subject_line to search for draft message
 * @return {object} GmailDraft object
 */
functionsubjectFilter_(subject_line){
return(element)=>{
if(element.getMessage().getSubject()===subject_line){
returnelement;
}
};
}
}
/**
 * Fill template string with data object
 * @see https://stackoverflow.com/a/378000/1027723
 * @param {string} template string containing {{}} markers which are replaced with data
 * @param {object} data object used to replace {{}} markers
 * @return {object} message replaced with data
 */
functionfillInTemplateFromObject_(template,data){
// We have two templates one for plain text and the html body
// Stringifing the object means we can do a global replace
lettemplate_string=JSON.stringify(template);
// Token replacement
template_string=template_string.replace(/{{[^{}]+}}/g,(key)=>{
returnescapeData_(data[key.replace(/[{}]+/g,"")]||"");
});
returnJSON.parse(template_string);
}
/**
 * Escape cell data to make JSON safe
 * @see https://stackoverflow.com/a/9204218/1027723
 * @param {string} str to escape JSON special characters from
 * @return {string} escaped string
 */
functionescapeData_(str){
returnstr
.replace(/[\\]/g,"\\\\")
.replace(/[\"]/g,'\\"')
.replace(/[\/]/g,"\\/")
.replace(/[\b]/g,"\\b")
.replace(/[\f]/g,"\\f")
.replace(/[\n]/g,"\\n")
.replace(/[\r]/g,"\\r")
.replace(/[\t]/g,"\\t");
}
}