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Deno SMTP mail client

IMPORTANT SECURITY INFORMATION

PLEASE update to a version >= 0.8! 0.8 has a problem where malformed mails could potatialy allow attackers to create a mail (with linebreaks) to send unwanted SMTP commands. This could result in authentic phishing attacks! Whith no way for the user to identify that this is a phishing mail! Or that this mail contains a dangorus attachment!

Also make shure that Mails are sent one after the other as they can corrupt each others data!

Allowed Mail Formats

A single Mail mail@example.de with a name NAME can be encoded in the following ways:

  1. "name@example.de"
  2. "<name@example.de>"
  3. "NAME <name@example.de>"
  4. {mail: "name@example.de"}
  5. {mail: "name@example.de", name: "NAME"}

Where 1-3 is called a “MailString”.

Multiple Mails can be an Array of the above OR a object that maps names to mails for example:

{"P1": "p1@example.de", "P2": "p2@example.de"} we call this a MailObject.

For the fields

  1. from, replyTo we only allow a “MailString”.
  2. to, cc, bcc we allow a MailObject a Array of single Mails or a single Mail.

Sending multiple mails

Note that for race-condition reasons we can’t send multiple mails at once. Because of that if send is allready called and still processing a mail client.send will que that sending.

Example

import { SmtpClient, quotedPrintableEncode } from "https://deno.land/x/denomailer/mod.ts";

const client = new SmtpClient();

await client.connect({
  hostname: "smtp.163.com",
  port: 25,
  username: "username",
  password: "password",
});

await client.send({
  from: "mailaddress@163.com",
  to: "Me <to-address@xx.com>",
  cc: [
    "name@example.de",
    "<name@example.de>",
    "NAME <name@example.de>",
    {mail: "name@example.de"},
    {mail: "name@example.de", name: "NAME"}
  ],
  bcc: {
    "Me": "to-address@xx.com"
  },
  subject: "Mail Title",
  content: "Mail Content",
  html: "<a href='https://github.com'>Github</a>",
  date: "12 Mar 2022 10:38:05 GMT",
  priority: "high",
  replyTo: 'mailaddress@163.com',
  attachments: [
    { encoding: "text"; content: 'Hi', contentType: 'text/plain', filename: 'text.txt' },
    { encoding: "base64"; content: '45dasjZ==', contentType: 'image/png', filename: 'img.png' },
    {
      content: new Uint8Array([0,244,123]),
      encoding: "binary",
      contentType: 'image/jpeg', 
      filename: 'bin.png'
    }
  ],
  mimeContent: [
    {
      mimeType: 'application/markdown',
      content: quotedPrintableEncode('# Title\n\nHello World!'),
      transferEncoding: 'quoted-printable'
    }
  ]
  
});

await client.close();

TLS connection

await client.connectTLS({
  hostname: "smtp.163.com",
  port: 465,
  username: "username",
  password: "password",
});

Use in Gmail

await client.connectTLS({
  hostname: "smtp.gmail.com",
  port: 465,
  username: "your username",
  password: "your password",
});

await client.send({
  from: "someone@163.com", // Your Email address
  to: "someone@xx.com", // Email address of the destination
  subject: "Mail Title",
  content: "Mail Content，maybe HTML",
});

await client.close();

Configuring your client

You can pass options to your client through the SmtpClient constructor.

import { SmtpClient } from "https://deno.land/x/denomailer/mod.ts";

//Defaults
const client = new SmtpClient({
  console_debug: true, // enable debugging this is good while developing should be false in production as Authentication IS LOGGED TO CONSOLE!
  unsecure: true, // allow unsecure connection to send authentication IN PLAIN TEXT and also mail content!
});