Dart
Force Quoted-Printable Encoding for Email

Demonstrates how to force the quoted-printable encoding for email.
Chilkat Dart Downloads

Dart
import 'package:chilkat/chilkat.dart';

void main() {
  final email = CkEmail();

  email.subject = 'test';
  email.from = 'bob@example.com';
  email.addTo('Mary', 'mary@example.com');

  // Add plain-text and HTML alternative bodies.
  // Include some "=" chars so we can see the quoted-printable encoding when used..
  email.addPlainTextAlternativeBody('This is a test == Hello World!');
  email.addHtmlAlternativeBody('<html><body>This is a test == Hello World!</body></html>');

  // Examine the MIME of the email to see that it does not use quoted-printable.
  // (If the email contained non-usascii chars, it would automatically use quoted-printable.)
  final mailman = CkMailMan();
  print(mailman.renderToMime(email));

  // Here is the MIME before forcing quoted-printable.
  // Notice the Content-Transfer-Encoding is "7bit" (not "quoted-printable")

  // MIME-Version: 1.0
  // Date: Tue, 29 Sep 2020 12:26:52 -0500
  // Message-ID: <CF274FC0A2F82B98A05B7507DF7DFB966A2C0EB8@CHILKATSLICE>
  // Content-Type: multipart/alternative;
  //  boundary="------------080901080902080000030208"
  // X-Priority: 3 (Normal)
  // Subject: test
  // From: bob@example.com
  // To: Mary <mary@example.com>
  // 
  // --------------080901080902080000030208
  // Content-Transfer-Encoding: 7bit
  // Content-Type: text/plain; charset=us-ascii; format=flowed
  // 
  // This is a test == Hello World!
  // --------------080901080902080000030208
  // Content-Transfer-Encoding: 7bit
  // Content-Type: text/html; charset=us-ascii
  // 
  // <html><body>This is a test == Hello World!</body></html>
  // --------------080901080902080000030208--

  print('----');

  // To force quoted-printable, set the Content-Transfer-Encoding header.
  // It will automatically propagate as needed to the MIME sub-parts.
  email.addHeaderField('Content-Transfer-Encoding', 'quoted-printable');
  print(mailman.renderToMime(email));

  // MIME-Version: 1.0
  // Date: Tue, 29 Sep 2020 12:26:52 -0500
  // Message-ID: <F36B276E3A720FE5111D15CE9142C8909E1F5AB9@CHILKATSLICE>
  // Content-Type: multipart/alternative;
  //  boundary="------------080901080902080000030208"
  // X-Priority: 3 (Normal)
  // Subject: test
  // From: bob@example.com
  // To: Mary <mary@example.com>
  // 
  // --------------080901080902080000030208
  // Content-Transfer-Encoding: quoted-printable
  // Content-Type: text/plain; charset=us-ascii; format=flowed
  // 
  // This is a test =3D=3D Hello World!
  // --------------080901080902080000030208
  // Content-Transfer-Encoding: quoted-printable
  // Content-Type: text/html; charset=us-ascii
  // 
  // <html><body>This is a test =3D=3D Hello World!</body></html>
  // --------------080901080902080000030208--
}