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. 
 */ 
 const 
  
 RECIPIENT_COL 
  
 = 
  
 "Recipient" 
 ; 
 const 
  
 EMAIL_SENT_COL 
  
 = 
  
 "Email Sent" 
 ; 
 /** 
 * Creates the menu item "Mail Merge" for user to run scripts on drop-down. 
 */ 
 function 
  
 onOpen 
 () 
  
 { 
  
 const 
  
 ui 
  
 = 
  
 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 
 */ 
 function 
  
 sendEmails 
 ( 
 subjectLine 
 , 
  
 sheet 
 = 
 SpreadsheetApp 
 . 
 getActiveSheet 
 ()) 
  
 { 
  
 // option to skip browser prompt if you want to use this code in other projects 
  
 if 
  
 ( 
 ! 
 subjectLine 
 ){ 
  
 subjectLine 
  
 = 
  
 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 
  
 ( 
 subjectLine 
  
 === 
  
 "cancel" 
  
 || 
  
 subjectLine 
  
 == 
  
 "" 
 ){ 
  
  
 // If no subject line, finishes up 
  
 return 
 ; 
  
 } 
  
 } 
  
 // Gets the draft Gmail message to use as a template 
  
 const 
  
 emailTemplate 
  
 = 
  
 getGmailTemplateFromDrafts_ 
 ( 
 subjectLine 
 ); 
  
 // Gets the data from the passed sheet 
  
 const 
  
 dataRange 
  
 = 
  
 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 
  
 const 
  
 data 
  
 = 
  
 dataRange 
 . 
 getDisplayValues 
 (); 
  
 // Assumes row 1 contains our column headings 
  
 const 
  
 heads 
  
 = 
  
 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 
  
 const 
  
 emailSentColIdx 
  
 = 
  
 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 
  
 const 
  
 obj 
  
 = 
  
 data 
 . 
 map 
 ( 
 r 
  
 = 
>  
 ( 
 heads 
 . 
 reduce 
 (( 
 o 
 , 
  
 k 
 , 
  
 i 
 ) 
  
 = 
>  
 ( 
 o 
 [ 
 k 
 ] 
  
 = 
  
 r 
 [ 
 i 
 ] 
  
 || 
  
 '' 
 , 
  
 o 
 ), 
  
 {}))); 
  
 // Creates an array to record sent emails 
  
 const 
  
 out 
  
 = 
  
 []; 
  
 // Loops through all the rows of data 
  
 obj 
 . 
 forEach 
 ( 
 function 
 ( 
 row 
 , 
  
 rowIdx 
 ){ 
  
 // Only sends emails if email_sent cell is blank and not hidden by a filter 
  
 if 
  
 ( 
 row 
 [ 
 EMAIL_SENT_COL 
 ] 
  
 == 
  
 '' 
 ){ 
  
 try 
  
 { 
  
 const 
  
 msgObj 
  
 = 
  
 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 
 ([ 
 new 
  
 Date 
 ()]); 
  
 } 
  
 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 
 */ 
  
 function 
  
 getGmailTemplateFromDrafts_ 
 ( 
 subject_line 
 ){ 
  
 try 
  
 { 
  
 // get drafts 
  
 const 
  
 drafts 
  
 = 
  
 GmailApp 
 . 
 getDrafts 
 (); 
  
 // filter the drafts that match subject line 
  
 const 
  
 draft 
  
 = 
  
 drafts 
 . 
 filter 
 ( 
 subjectFilter_ 
 ( 
 subject_line 
 ))[ 
 0 
 ]; 
  
 // get the message object 
  
 const 
  
 msg 
  
 = 
  
 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 
  
 const 
  
 allInlineImages 
  
 = 
  
 draft 
 . 
 getMessage 
 (). 
 getAttachments 
 ({ 
 includeInlineImages 
 : 
  
 true 
 , 
 includeAttachments 
 : 
 false 
 }); 
  
 const 
  
 attachments 
  
 = 
  
 draft 
 . 
 getMessage 
 (). 
 getAttachments 
 ({ 
 includeInlineImages 
 : 
  
 false 
 }); 
  
 const 
  
 htmlBody 
  
 = 
  
 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) 
  
 const 
  
 img_obj 
  
 = 
  
 allInlineImages 
 . 
 reduce 
 (( 
 obj 
 , 
  
 i 
 ) 
  
 = 
>  
 ( 
 obj 
 [ 
 i 
 . 
 getName 
 ()] 
  
 = 
  
 i 
 , 
  
 obj 
 ) 
  
 ,{}); 
  
 //Regexp searches for all img string positions with cid 
  
 const 
  
 imgexp 
  
 = 
  
 RegExp 
 ( 
 '<img.*?src="cid:(.*?)".*?alt="(.*?)"[^\>]+>' 
 , 
  
 'g' 
 ); 
  
 const 
  
 matches 
  
 = 
  
 [... 
 htmlBody 
 . 
 matchAll 
 ( 
 imgexp 
 )]; 
  
 //Initiates the allInlineImages object 
  
 const 
  
 inlineImagesObj 
  
 = 
  
 {}; 
  
 // built an inlineImagesObj from inline image matches 
  
 matches 
 . 
 forEach 
 ( 
 match 
  
 = 
>  
 inlineImagesObj 
 [ 
 match 
 [ 
 1 
 ]] 
  
 = 
  
 img_obj 
 [ 
 match 
 [ 
 2 
 ]]); 
  
 return 
  
 { 
 message 
 : 
  
 { 
 subject 
 : 
  
 subject_line 
 , 
  
 text 
 : 
  
 msg 
 . 
 getPlainBody 
 (), 
  
 html 
 : 
 htmlBody 
 }, 
  
  
 attachments 
 : 
  
 attachments 
 , 
  
 inlineImages 
 : 
  
 inlineImagesObj 
  
 }; 
  
 } 
  
 catch 
 ( 
 e 
 ) 
  
 { 
  
 throw 
  
 new 
  
 Error 
 ( 
 "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 
 */ 
  
 function 
  
 subjectFilter_ 
 ( 
 subject_line 
 ){ 
  
 return 
  
 function 
 ( 
 element 
 ) 
  
 { 
  
 if 
  
 ( 
 element 
 . 
 getMessage 
 (). 
 getSubject 
 () 
  
 === 
  
 subject_line 
 ) 
  
 { 
  
 return 
  
 element 
 ; 
  
 } 
  
 } 
  
 } 
  
 } 
  
 /** 
 * 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 
 */ 
  
 function 
  
 fillInTemplateFromObject_ 
 ( 
 template 
 , 
  
 data 
 ) 
  
 { 
  
 // We have two templates one for plain text and the html body 
  
 // Stringifing the object means we can do a global replace 
  
 let 
  
 template_string 
  
 = 
  
 JSON 
 . 
 stringify 
 ( 
 template 
 ); 
  
 // Token replacement 
  
 template_string 
  
 = 
  
 template_string 
 . 
 replace 
 ( 
 /{{[^{}]+}}/g 
 , 
  
 key 
  
 = 
>  
 { 
  
 return 
  
 escapeData_ 
 ( 
 data 
 [ 
 key 
 . 
 replace 
 ( 
 /[{}]+/g 
 , 
  
 "" 
 )] 
  
 || 
  
 "" 
 ); 
  
 }); 
  
 return 
  
 JSON 
 . 
 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 
 */ 
  
 function 
  
 escapeData_ 
 ( 
 str 
 ) 
  
 { 
  
 return 
  
 str 
  
 . 
 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' 
 ); 
  
 }; 
 }