A simple LUA script to send an e-mail with an attachment.

email_sendfile.lua

-- requires an SMTP server to send emails

local smtp = require("socket.smtp")
local ltn12 = require("ltn12")
local mime = require("mime")

from = "<me@my.email.com>"

rcpt = {
  "<somebob@testemail.com>"
}

-- the multipart message definition
mesgt = {
  headers = {
    to = "Bob <somebob@testemail.com>",
    subject = "Sending attachment over e-mail test"
  },
  body = {
    -- the message content
    [1] = {
        body = "Sending you a nice file! :D"
    },
    -- the file attachment
    [2] = {
        headers = {
                    ["content-type"] = 'attachment; name="testfile.bin"',
                    ["content-disposition"] = 'attachment; filename="testfile.bin"',
                    ["content-description"] = 'test binary file',
                    ["content-transfer-encoding"] = "BASE64"
        },
        body = ltn12.source.chain(
                ltn12.source.file( io.open( "/path/to/testfile.bin", "rb")),
                ltn12.filter.chain(
                        mime.encode("base64"),
                        mime.wrap()
                )
        )
     }
  }
}

-- send the message
r, e = smtp.send{
  from = from,
  rcpt = rcpt,
  source = smtp.message(mesgt)
}