(CkPython) Send DKIM Signed Email

Demonstrates how to send DKIM signed email.

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux, Solaris

import sys
import chilkat

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

mailman = chilkat.CkMailMan()
dkim = chilkat.CkDkim()

# SMTP server settings...
mailman.put_SmtpHost("SMTP_DOMAIN")
mailman.put_SmtpUsername("SMTP_LOGIN")
mailman.put_SmtpPassword("SMTP_PASSWORD")
mailman.put_SmtpPort(465)
mailman.put_SmtpSsl(True)

email = chilkat.CkEmail()

email.put_Subject("This is a test")
email.put_Body("This is a test")
email.put_From("Chilkat Support <support@chilkatsoft.com>")

# Add some recipients (BCC recipients are added below)
email.AddTo("Chilkat Software","chilkat_software@yahoo.com")
email.AddTo("Chilkat Admin","admin@chilkatsoft.com")
email.AddCC("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...
bdMime = chilkat.CkBinData()
success = mailman.RenderToMimeBd(email,bdMime)
if (success != True):
    print(mailman.lastErrorText())
    sys.exit()

# 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.put_DkimDomain("chilkatsoft.com")
dkim.put_DkimSelector("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.
password = "passwd"
privKey = chilkat.CkPrivateKey()
success = privKey.LoadAnyFormatFile("qa_data/pem/rsa_passwd.pem",password)
if (success != True):
    print(privKey.lastErrorText())
    sys.exit()

success = dkim.SetDkimPrivateKey(privKey)
if (success != True):
    print(dkim.lastErrorText())
    sys.exit()

# Add the DKIM-Signature header to the MIME in bdMime
success = dkim.DkimSign(bdMime)
if (success != True):
    print(dkim.lastErrorText())
    sys.exit()

# If desired, examine the MIME of the email being sent.
bdMime.WriteFile("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")
strRecipients = "chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com"
strFrom = "support@chilkatsoft.com"

success = mailman.SendMimeBd(strFrom,strRecipients,bdMime)
if (success != True):
    print(mailman.lastErrorText())
    sys.exit()

success = mailman.CloseSmtpConnection()
if (success != True):
    print("Connection to SMTP server not closed cleanly.")

print("DKIM Signed Mail Sent!")