Feature mime base64 encoding

README.md

@@ -132,6 +132,11 @@ export interface ClientOptions {
      * - ...
      */
     preprocessors?: Preprocessor[];
+    /**
+     * Set the encoding for the mail content
+     * @default quoted-printable
+     */
+    mimeEncoding?: "quoted-printable" | "base64";
   };
 }
 ```
@@ -180,6 +185,9 @@ It takes a preprocessed email config (ResolvedSendConfig) and the preprocessed
 client options (ResolvedClientOptions) and returns a possibly modified email
 config.
 
+You can change the encoding of the mail subject and content with `mimeEncoding`.
+`mimeEncoding: quoted-printable` (default).
+
 #### pool
 
 With a normal SMTP client, emails are sent one after the other so if you have a
@@ -234,7 +242,8 @@ const client = new SMTPClient({
   },
   client: {
     warning: "log",
-    preprocessors: [filterBurnerMails],
+    preprocessors: [filterBurnerMails], 
+    mimeEncoding: "base64",
   },
   debug: {
     log: false,
@@ -263,6 +272,7 @@ export interface SendConfig {
   subject: string;
   content?: string;
   mimeContent?: Content[];
+  mimeEncoding?: "quoted-printable" | "base64";
   html?: string;
   inReplyTo?: string;
   replyTo?: string;
@@ -289,6 +299,11 @@ Add custom headers to the email.
 There may be instances where you want to use your own encoding. This option
 allows you to specify the content of the mail.
 
+#### mimeEncoding
+
+Subject and Content are encoded with `quoted-printable` by default. You can change it to `base64`.
+this `mimeEncoding` can overwrite Client's default `mimeEncoding`.
+
 #### content & html
 
 The content should be a plain-text version of the HTML content. You can set

client/mod.ts

@@ -135,6 +135,9 @@ export class SMTPHandler {
    * @returns nothing (for now as this might change in the future!)
    */
   send(config: SendConfig): Promise<void> {
+    if(config.mimeEncoding == null && this.#clientConfig.client.mimeEncoding != null){
+      config.mimeEncoding = this.#clientConfig.client.mimeEncoding;
+    }
     let resolvedConfig = resolveSendConfig(config);
 
     for (let i = 0; i < this.#clientConfig.client.preprocessors.length; i++) {

config/client.ts

@@ -23,6 +23,7 @@ export interface ResolvedClientOptions {
   client: {
     warning: "ignore" | "log" | "error";
     preprocessors: Preprocessor[];
+    mimeEncoding?: "quoted-printable" | "base64";
   };
 }
 
@@ -106,6 +107,11 @@ export interface ClientOptions {
      * - ...
      */
     preprocessors?: Preprocessor[];
+    /**
+     * Set the encoding for the mail content
+     * @default quoted-printable
+     */
+    mimeEncoding?: "quoted-printable" | "base64";
   };
 }
 
@@ -144,6 +150,7 @@ export function resolveClientOptions(
     client: {
       warning: config.client?.warning ?? "log",
       preprocessors: config.client?.preprocessors ?? [],
+      mimeEncoding: config.client?.mimeEncoding ?? "quoted-printable",
     },
   };
 }

config/mail/content.ts

@@ -1,4 +1,4 @@
-import { quotedPrintableEncode } from "./encoding.ts";
+import {mimeEncode, quotedPrintableEncode} from "./encoding.ts";
 
 export interface Content {
   mimeType: string;
@@ -10,10 +10,12 @@ export function resolveContent({
   text,
   html,
   mimeContent,
+  mimeEncoding
 }: {
   text?: string;
   html?: string;
   mimeContent?: Content[];
+  mimeEncoding?: "quoted-printable" | "base64";
 }): Content[] {
   const newContent = [...mimeContent ?? []];
 
@@ -27,16 +29,16 @@ export function resolveContent({
   if (text) {
     newContent.push({
       mimeType: 'text/plain; charset="utf-8"',
-      content: quotedPrintableEncode(text),
-      transferEncoding: "quoted-printable",
+      content: mimeEncode(text, mimeEncoding),
+      transferEncoding: mimeEncoding,
     });
   }
 
   if (html) {
     newContent.push({
       mimeType: 'text/html; charset="utf-8"',
-      content: quotedPrintableEncode(html),
-      transferEncoding: "quoted-printable",
+      content: mimeEncode(html),
+      transferEncoding: mimeEncoding,
     });
   }
 

config/mail/encoding.ts

@@ -1,7 +1,24 @@
 export { base64Decode, base64Encode } from "../../deps.ts";
+import { base64Encode } from "../../deps.ts";
 
 const encoder = new TextEncoder();
 
+export function mimeEncode(data: string, encoding?: string) {
+  if(encoding === "base64"){
+    return base64EncodeWrapLine(data);
+  }else{
+    return quotedPrintableEncode(data);
+  }
+}
+
+export function mimeEncodeInline(data: string, encoding?: string) {
+  if(encoding === "base64"){
+    return base64EncodeInline(data);
+  }else{
+    return quotedPrintableEncodeInline(data);
+  }
+}
+
 /**
  * Encodes a string as quotedPrintable
  *
@@ -41,16 +58,20 @@ export function quotedPrintableEncode(data: string, encLB = false) {
   const lines = Math.ceil(encodedData.length / 74) - 1;
 
   let offset = 0;
+  let offsetWrapChars = "";
   for (let i = 0; i < lines; i++) {
     let old = encodedData.slice(i * 74 + offset, (i + 1) * 74);
     offset = 0;
+    offsetWrapChars = "";
 
     if (old.at(-1) === "=") {
+      offsetWrapChars = old.slice(old.length - 1, old.length);
       old = old.slice(0, old.length - 1);
       offset = -1;
     }
 
     if (old.at(-2) === "=") {
+      offsetWrapChars = old.slice(old.length - 2, old.length);
       old = old.slice(0, old.length - 2);
       offset = -2;
     }
@@ -62,8 +83,12 @@ export function quotedPrintableEncode(data: string, encLB = false) {
     }
   }
 
+  if(offsetWrapChars !== "" && !offsetWrapChars.startsWith("=")) {
+    offsetWrapChars = "=" + offsetWrapChars;
+  }
+
   // Add rest with no new line
-  ret += encodedData.slice(lines * 74);
+  ret += offsetWrapChars + encodedData.slice(lines * 74);
 
   return ret;
 }
@@ -74,9 +99,42 @@ function hasNonAsciiCharacters(str: string) {
 }
 
 export function quotedPrintableEncodeInline(data: string) {
-  if (hasNonAsciiCharacters(data) || data.startsWith("=?")) {
+  if (data.startsWith("=?")) {
     return `=?utf-8?Q?${quotedPrintableEncode(data)}?=`;
   }
+  if(hasNonAsciiCharacters(data)){
+    data = quotedPrintableEncode(data).split("\r\n").map((l, i) => {
+	    if(l.endsWith("=")){
+		    // strip "=" that was appended by quotedPrintableEncode, but don't need for single line's =??= encoding
+        	l = l.substring(0, l.length - 1);
+	    }
+		return `${i>0?" ":""}=?utf-8?Q?${l}?=`;
+    }).join("\r\n");
+  }
 
   return data;
 }
+
+export function base64EncodeWrapLine(data: string) {
+  const maxlen = 60;
+  const base64Data = base64Encode(data);
+
+  let encodedLines = [];
+  for (
+      let line = 0;
+      line < Math.ceil(base64Data.length / maxlen);
+      line++
+  ) {
+    const lineOfBase64 = base64Data.slice(
+        line * maxlen,
+        (line + 1) * maxlen,
+    );
+    encodedLines.push(lineOfBase64);
+  }
+  return encodedLines.join("\r\n");
+}
+
+export function base64EncodeInline(data: string) {
+  const encodedLines = base64EncodeWrapLine(data);
+  return encodedLines.split("\r\n").map((l, i) => `${i>0?" ":""}=?utf-8?B?${l}?=`).join("\r\n");
+}

config/mail/mod.ts

@@ -14,7 +14,7 @@ import {
 } from "./email.ts";
 import { ResolvedClientOptions } from "../client.ts";
 import { Headers, validateHeaders } from "./headers.ts";
-import { quotedPrintableEncodeInline } from "./encoding.ts";
+import {mimeEncodeInline, quotedPrintableEncodeInline} from "./encoding.ts";
 /**
  * Config for a mail
  */
@@ -27,6 +27,7 @@ export interface SendConfig {
   subject: string;
   content?: string;
   mimeContent?: Content[];
+  mimeEncoding?: "quoted-printable" | "base64";
   html?: string;
   inReplyTo?: string;
   replyTo?: string;
@@ -49,6 +50,7 @@ export interface ResolvedSendConfig {
   date: string;
   subject: string;
   mimeContent: Content[];
+  mimeEncoding?: "quoted-printable" | "base64";
   inReplyTo?: string;
   replyTo?: saveMailObject;
   references?: string;
@@ -68,6 +70,7 @@ export function resolveSendConfig(config: SendConfig): ResolvedSendConfig {
     subject,
     content,
     mimeContent,
+    mimeEncoding,
     html,
     inReplyTo,
     replyTo,
@@ -86,12 +89,13 @@ export function resolveSendConfig(config: SendConfig): ResolvedSendConfig {
     date,
     mimeContent: resolveContent({
       mimeContent,
+      mimeEncoding,
       html,
       text: content,
     }),
     replyTo: replyTo ? parseSingleEmail(replyTo) : undefined,
     inReplyTo,
-    subject: quotedPrintableEncodeInline(subject),
+    subject: mimeEncodeInline(subject, mimeEncoding),
     attachments: attachments
       ? attachments.map((attachment) => resolveAttachment(attachment))
       : [],

test/encoding/base64.test.ts

@@ -0,0 +1,39 @@
+import { assertEquals } from "https://deno.land/[email protected]/testing/asserts.ts";
+import {base64Encode, base64EncodeInline, base64EncodeWrapLine} from "../../config/mail/encoding.ts";
+
+Deno.test("test base64 encode ascii", () => {
+  const encodedString = base64EncodeWrapLine("test");
+  assertEquals(encodedString, "dGVzdA==");
+});
+
+Deno.test("test base64 encode multibyte('test' meaning in Japanese)", () => {
+  const encodedString = base64EncodeWrapLine("テスト");
+  assertEquals(encodedString, "44OG44K544OI");
+});
+
+Deno.test("test base64 encode multibyte multi lines", () => {
+  const encodedString = base64EncodeWrapLine("これは日本語のメールだよ。QP対象のMultiByteが問題になっていたので日本語以外も同様のはず。");
+  assertEquals(encodedString, "44GT44KM44Gv5pel5pys6Kqe44Gu44Oh44O844Or44Gg44KI44CCUVDlr77o\r\n" +
+      "saHjga5NdWx0aUJ5dGXjgYzllY/poYzjgavjgarjgaPjgabjgYTjgZ/jga7j\r\n" +
+      "gafml6XmnKzoqp7ku6XlpJbjgoLlkIzmp5jjga7jga/jgZrjgII=");
+});
+
+Deno.test("test base64 encode inline", () => {
+  const encodedString = base64EncodeInline("test");
+  assertEquals(encodedString, "=?utf-8?B?dGVzdA==?=");
+});
+
+Deno.test("test base64 encode inline multibytes", () => {
+  const encodedString = base64EncodeInline("テスト");
+  assertEquals(encodedString, "=?utf-8?B?44OG44K544OI?=");
+});
+
+Deno.test("test base64 encode inline multibytes and multi lines", () => {
+  const encodedString = base64EncodeInline("これは日本語のメールだよ。QP対象のMultiByteが問題になっていたので日本語以外も同様のはず。");
+  assertEquals(encodedString, "=?utf-8?B?44GT44KM44Gv5pel5pys6Kqe44Gu44Oh44O844Or44Gg44KI44CCUVDlr77o?=\r\n" +
+      " =?utf-8?B?saHjga5NdWx0aUJ5dGXjgYzllY/poYzjgavjgarjgaPjgabjgYTjgZ/jga7j?=\r\n" +
+      " =?utf-8?B?gafml6XmnKzoqp7ku6XlpJbjgoLlkIzmp5jjga7jga/jgZrjgII=?=");
+});
+
+
+

test/encoding/quotedprintable.test.ts

@@ -0,0 +1,63 @@
+import { assertEquals } from "https://deno.land/[email protected]/testing/asserts.ts";
+import {quotedPrintableEncode, quotedPrintableEncodeInline} from "../../config/mail/encoding.ts";
+
+Deno.test("test quoted-printable encode ascii", () => {
+  const encodedString = quotedPrintableEncode("test");
+  assertEquals(encodedString, "test");
+});
+
+Deno.test("test quoted-printable encode multibyte('test' meaning in Japanese)", () => {
+  const encodedString = quotedPrintableEncode("テスト");
+  assertEquals(encodedString, "=e3=83=86=e3=82=b9=e3=83=88");
+});
+
+Deno.test("test quoted-printable encode multibyte('mail' meaning in Japanese)", () => {
+  const encodedString = quotedPrintableEncode("メール");
+  assertEquals(encodedString, "=e3=83=a1=e3=83=bc=e3=83=ab");
+});
+
+Deno.test("test quoted-printable encode multibyte [email protected]", () => {
+  const encodedString = quotedPrintableEncode("これは日本語のメールだよ");
+  assertEquals(encodedString, "=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte offset check +1 [email protected]", () => {
+  const encodedString = quotedPrintableEncode("1これは日本語のメールだよ");
+  assertEquals(encodedString, "1=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte offset check +2 [email protected]", () => {
+  const encodedString = quotedPrintableEncode("12これは日本語のメールだよ");
+  assertEquals(encodedString, "12=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte offset check +3 [email protected]", () => {
+  const encodedString = quotedPrintableEncode("123これは日本語のメールだよ");
+  assertEquals(encodedString, "123=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=\r\n=a1=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte [email protected] multi lines", () => {
+  const encodedString = quotedPrintableEncode("これは日本語のメールだよ。QP対象のMultiByteが問題になっていたので日本語以外も同様のはず。");
+  assertEquals(encodedString, "=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n"
+      + "=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88=e3=80=82QP=e5=af=be=e8=b1=a1=e3=81=aeMu=\r\n"
+      + "ltiByte=e3=81=8c=e5=95=8f=e9=a1=8c=e3=81=ab=e3=81=aa=e3=81=a3=e3=81=a6=e3=\r\n"
+      + "=81=84=e3=81=9f=e3=81=ae=e3=81=a7=e6=97=a5=e6=9c=ac=e8=aa=9e=e4=bb=a5=e5=a4=\r\n"
+      + "=96=e3=82=82=e5=90=8c=e6=a7=98=e3=81=ae=e3=81=af=e3=81=9a=e3=80=82");
+
+});
+
+Deno.test("test quoted-printable encode inline", () => {
+  const encodedString = quotedPrintableEncodeInline("test");
+  assertEquals(encodedString, "test");
+});
+
+Deno.test("test quoted-printable encode inline multibytes", () => {
+  const encodedString = quotedPrintableEncodeInline("テスト");
+  assertEquals(encodedString, "=?utf-8?Q?=e3=83=86=e3=82=b9=e3=83=88?=");
+});
+
+Deno.test("test quoted-printable encode inline multibytes and multi lines", () => {
+  const encodedString = quotedPrintableEncodeInline("これは日本語のメールだよ");
+  assertEquals(encodedString, "=?utf-8?Q?=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1?=\r\n" +
+      " =?utf-8?Q?=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88?=");
+});