Lua

Send DKIM Signed Email

See more DKIM / DomainKey Examples

Demonstrates how to send DKIM signed email. Lua

local chilkat = require("chilkat")

-- This example requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

local mailman = chilkat.MailMan.new()
local dkim = chilkat.Dkim.new()

-- SMTP server settings...
mailman.smtp_host = "SMTP_DOMAIN"
mailman.smtp_username = "SMTP_LOGIN"
mailman.smtp_password = "SMTP_PASSWORD"
mailman.smtp_port = 465
mailman.smtp_ssl = true

local email = chilkat.Email.new()

email.subject = "This is a test"
email.body = "This is a test"
email.from = "Chilkat Support <support@chilkatsoft.com>"

-- Add some recipients (BCC recipients are added below)
email:add_to("Chilkat Software", "chilkat_software@yahoo.com")
email:add_to("Chilkat Admin", "admin@chilkatsoft.com")
email:add_cc("Chilkat Admin", "admin@chilkat.io")

-- When sending an email with a DKIM signature, the MIME
-- of the email must not be modified prior to
-- or during the sending process.  Therefore, the MIME of the
-- email is assembled, the DKIM signature is added, and then
-- SendMimeBd is called to send the email.

-- First get the MIME of the email.  Calling RenderToMimeBd
-- causes the email to be signed and/or encrypted if those options
-- have been selected.  The MIME returned by RenderToMimeBd
-- is the exact MIME that would've been sent if SendEmail was
-- called.  We'll add a DKIM signature header to this MIME and then send...
local bdMime = chilkat.BinData.new()
local success = mailman:render_to_mime_bd(email, bdMime)
if not success then
    print(mailman.last_error_text)
    return
end

-- To create a DKIM signature,
-- you'll need to provide the following:
-- (1) An RSA private key in any common file format.
-- (2) The domain name (typically the same domain
-- as the sender of an email).
-- (3) A selector for the domain name -- an arbitrary string
-- to identify the matching public key in DNS.

-- To allow an email recipient to verify the DKIM signature via an
-- external email client supporting DKIM or using other software,
-- you will need to create a DNS record with the selector
-- and matching public key.  This example does not provide
-- information about DKIM DNS record creation.
-- (Chilkat does not provide an API for creating DNS records.
-- Creating the DKIM DNS record is something you would do
-- manually.)

-- Set the domain and selector:
-- You'll need to provide your own values here..
dkim.dkim_domain = "chilkatsoft.com"
dkim.dkim_selector = "brisbane"

-- Load a private key from any common RSA private key
-- format, such as DER, PKCS8, PEM, XML, etc.
-- The LoadDkimPkFile method automatically detects
-- the file format and reads it appropriately.
-- If a password is not required, you'll still need to provide
-- an empty password string argument, but it is ignored.
local password = "passwd"
local privKey = chilkat.PrivateKey.new()
success = privKey:load_any_format_file("qa_data/pem/rsa_passwd.pem", password)
if not success then
    print(privKey.last_error_text)
    return
end

success = dkim:set_dkim_private_key(privKey)
if not success then
    print(dkim.last_error_text)
    return
end

-- Add the DKIM-Signature header to the MIME in bdMime
success = dkim:dkim_sign(bdMime)
if not success then
    print(dkim.last_error_text)
    return
end

-- If desired, examine the MIME of the email being sent.
bdMime:write_file("qa_output/dkimSigned.eml")

-- ---- Prepare to send the email contained in bdMime ---

-- To send to multiple email addresses, the strRecipients should be set to a comma-separated
-- list of email addresses.

-- Note: This is where we can add additional BCC addreses.
-- Here we are adding "chilkat.support@gmail.com" as an additional BCC address.
-- Notice that the 1st three email addresses are NOT BCC because these email addresses
-- appear in the MIME header of the email (in the "To" and "CC" header fields).
-- A BCC email address does not appear in the MIME, and thus the non-BCC recipients cannot see
-- that the email was also sent to the BCC address.  (BCC means "blind carbon copy")
local strRecipients = "chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com"
local strFrom = "support@chilkatsoft.com"

success = mailman:send_mime_bd(strFrom, strRecipients, bdMime)
if not success then
    print(mailman.last_error_text)
    return
end

success = mailman:close_smtp_connection()
if not success then
    print("Connection to SMTP server not closed cleanly.")
end

print("DKIM Signed Mail Sent!")