Send raw email with attachment with AWS SES using Typescript

index.ts

/*
 * This solution was built based on stackoverflow answer https://stackoverflow.com/a/54233102
 * placed by user https://stackoverflow.com/users/2485910/snowball 
 */

import AWS from 'aws-sdk';
import {Template} from 'aws-sdk/clients/ses';

interface Attachment {
  encoding: 'base64';
  filename: string; // test.pdf
  content: string; // base64 value
  contentType: 'text/plain' | 'application/pdf' | 'image/gif';
}

/**
 * Send email with attachment
 * @param address
 * @param template
 * @param attachment
 * @returns
 */
const sendRawEmail = (
  address: string[],
  template: Template,
  attachment: Attachment
): Promise<any> => {
  return new Promise((resolve, reject) => {
    const ses = new AWS.SES({
      accessKeyId: process.env.AMZ_ACCESS_KEY,
      secretAccessKey: process.env.AMZ_SECRET_KEY,
      region: process.env.REGION,
    });
    const date = new Date();
    const boundary = `----=_Part${Math.random().toString().substr(2)}`;
    const rawMessage = [
      `From: ${process.env.FROM_EMAIL}`, // Can be just the email as well without <>
      `To: ${address[0]}`,
      `Subject: ${template.SubjectPart}`,
      `MIME-Version: 1.0`,
      `Date: ${formatDate(date)}`, // Will be replaced by SES
      `Content-Type: multipart/alternative; boundary="${boundary}"`, // For sending both plaintext & html content
      // ... you can add more headers here as decribed in https://docs.aws.amazon.com/ses/latest/DeveloperGuide/header-fields.html
      `\n`,
      `--${boundary}`,
      `Content-Type: text/plain; charset=UTF-8`,
      `Content-Transfer-Encoding: 7bit`,
      `\n`,
      template.TextPart,
      `--${boundary}`,
      `Content-Type: text/html; charset=UTF-8`,
      `Content-Transfer-Encoding: 7bit`,
      `\n`,
      template.HtmlPart,
      `\n`,
      `--${boundary}`,
      `Content-Type: text/plain; name="${attachment.filename}"`,
      `Content-Description: ${attachment.filename}`,
      `Content-Disposition: attachment;filename="${attachment.filename}";`,
      `creation-date="${formatDate(date)}"`,
      `Content-Transfer-Encoding: ${attachment.encoding}`,
      `\n`,
      attachment.content,
      `\n`,
      `--${boundary}--`,
    ];

    const params: AWS.SES.Types.SendRawEmailRequest = {
      Destinations: address,
      RawMessage: {
        Data: rawMessage.join('\n'),
      },
      Source: process.env.FROM_EMAIL, // Must be verified within AWS SES
      // ConfigurationSetName: configuration_set, // optional AWS SES configuration set for open & click tracking
      Tags: [
        // ... optional email tags
      ],
    };

    ses.sendRawEmail(params, (err: any, data: any) => {
      if (err) {
        return reject(err);
      } else {
        return resolve(data);
      }
    });
  });
};

/**
 * Outputs timezone offset in format ZZ
 * @param date
 * @returns
 */
const getOffset = (date: Date) => {
  var offset = -date.getTimezoneOffset();
  var offsetHours = Math.abs(Math.floor(offset / 60));
  var offsetMinutes = Math.abs(offset) - offsetHours * 60;

  var offsetSign = offset > 0 ? '+' : '-';

  return (
    offsetSign + ('0' + offsetHours).slice(-2) + ('0' + offsetMinutes).slice(-2)
  );
};

/**
 * Outputs two digit inputs with leading zero
 * @param input
 * @returns
 */
const leadingZero = (input: number) => ('0' + input).slice(-2);

/**
 * Formats date in ddd, DD MMM YYYY HH:MM:SS ZZ
 * @param date
 * @returns
 */
const formatDate = (date: Date) => {
  var weekdays = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'];
  var months = [
    'Jan',
    'Feb',
    'Mar',
    'Apr',
    'May',
    'Jun',
    'Jul',
    'Aug',
    'Sep',
    'Oct',
    'Nov',
    'Dec',
  ];
  var weekday = weekdays[date.getDay()];
  var day = leadingZero(date.getDate());
  var month = months[date.getMonth()];
  var year = date.getFullYear();
  var hour = leadingZero(date.getHours());
  var minute = leadingZero(date.getMinutes());
  var second = leadingZero(date.getSeconds());
  var offset = getOffset(date);

  return `${weekday}, ${day} ${month} ${year} ${hour}:${minute}:${second} ${offset}`;
};