Use Mailgun to send a pdf attachment from Base64 string

Question

I have a pdf that is being generated by another function, which returns a Base64 string. I would like to then attach it to a Mailgun email as attachment, which is built into Meteor and Mailgun. I see that there is a lot of examples of attaching a file from the file system, but I don't see anything using Base64.

I have a method that generates a Base64 string and concatonates with prefix in order to convert Base64 to PDF:

//returns base64 string: looks like "YW55IGNhcm5hbCBwbGVhc3VyZQ=="
const base64AttachmentString = 'data:application/pdf;base64,' + generatePdfBase64();

import { Email } from "meteor/email";

Email.send({
  to: "email@example.com",
  from: "John Smith <johnsmith@example.com>",
  subject: "Sending Base64 as PDF",
  html: generatedHTMLTemplate,
  attachment: base64AttachmentString
});

Is there a way to send a Base64 attachment where Mailgun will recognize it as a PDF? I know this is possible with other mailers such as Nodemailer and SendGrid.

Dekel · Accepted Answer · 2020-04-03T18:37:53.860

It seems like meteor's Email requires you to add the attachments keys, which should be an array of attachments.

As for the options for the attachments - there are multiple:

    {   // utf-8 string as an attachment
        filename: 'text1.txt',
        content: 'hello world!'
    },
    {   // binary buffer as an attachment
        filename: 'text2.txt',
        content: new Buffer('hello world!','utf-8')
    },
    {   // file on disk as an attachment
        filename: 'text3.txt',
        path: '/path/to/file.txt' // stream this file
    },
    {   // filename and content type is derived from path
        path: '/path/to/file.txt'
    },
    {   // stream as an attachment
        filename: 'text4.txt',
        content: fs.createReadStream('file.txt')
    },
    {   // define custom content type for the attachment
        filename: 'text.bin',
        content: 'hello world!',
        contentType: 'text/plain'
    },
    {   // use URL as an attachment
        filename: 'license.txt',
        path: 'https://raw.github.com/andris9/Nodemailer/master/LICENSE'
    },
    {   // encoded string as an attachment
        filename: 'text1.txt',
        content: 'aGVsbG8gd29ybGQh',
        encoding: 'base64'
    },
    {   // data uri as an attachment
        path: 'data:text/plain;base64,aGVsbG8gd29ybGQ='
    }

Specifically in your example you can use:

const base64AttachmentString = 'data:application/pdf;base64,' + generatePdfBase64();

import { Email } from "meteor/email";

Email.send({
  to: "email@example.com",
  from: "John Smith <johnsmith@example.com>",
  subject: "Sending Base64 as PDF",
  html: generatedHTMLTemplate,
  attachments: [
    {
      path: base64AttachmentString
    }
  ]
});

Would I need to include any multipart/form-data encoding when sending attachment? — maudulus, Apr 03 '20 at 17:24
Pretty sure that you don't need that. Please check and update. — Dekel, Apr 03 '20 at 17:51
It's not working as is - just sending with no attachment. The string is logging, however. — maudulus, Apr 03 '20 at 17:58
If you want to use the Buffer (from my previous example) you should use `content` and not `path`. — Dekel, Apr 03 '20 at 19:49

Use Mailgun to send a pdf attachment from Base64 string

1 Answers1