The following vb6 example codes demonstrate how to add DomainKeys and DKIM signature to email and send it using SMTP server.
DKIM and DomainKeys
DomainKeys is a technology proposal that can bring black and white back to this decision process by giving email providers a mechanism for verifying both the domain of each email sender and the integrity of the messages sent. To learn more detail about DomainKeys, please refer to http://antispam.yahoo.com/domainkeys
DKIM is a similar technology as Domainkeys. To learn more detail about DKIM, please refer to RFC4871.
Before you can add DomainKeys and DKIM signature to email, you need to generate the certificate and X-DK-File like this:
Download Certificate for your DomainKeys/DKIM key pair
Please click here to go to this online tool at first. Then input your email sender domain in it and click “Download Certificate” and save the downloaded *.pfx file to your local disk. This file contains your DomainKeys and DKIM key pair.
To sign the DomainKeys with EASendMail, we also need to create a text file with notepad and save it.
For example: We create a emailarchitectdomainkeys.txt and contains the following content:
dk_d: emailarchitect.net dk_s: s1024 PFXPath: c:\my cert\emailarchitect.pfx PFXPassword: mypassword DKIM: yes DomainKey: no // dk_d is the email sender domain, // dk_s is the domain public key selector. // PFXPath is the PFX file full path. // PFXPassword is the PFX file password. // because DomainKeys is obsolete, so set it to no
We also need to deploy the certificate Public Key to your domain DNS server. You can export the public key by the online tool:
Deploy Public Key
Once you get the public key, you should set a TXT record in your domain DNS server. For example: your selector is s1024, your domain is emailarchitect.net, and then you should create a TXT record for s1024._domainkey.emailarchitect.net and set the following content in the record.
s1024._domainkey.emailarchitect.net text = "t=y; k=rsa; p=MIGfMA0GCSqGS...hSinuQIDAQAB"
To learn more detail about Public Key deployment, please refer to http://antispam.yahoo.com/domainkeys
EASendMail is a SMTP component which supports all operations of SMTP/ESMTP protocols (RFC 821, RFC 822, RFC 2554). Before you can use the following example codes, you should download the EASendMail Installer and install it on your machine at first.
To use EASendMail SMTP ActiveX Object in your project, the first step is “Add reference
of EASendMail to your project”. Please select menu ->
EASendMailObj ActiveX Object, click
OK, the reference will be added
to current project, and you can start to use it to send email in your VB6 project.
Open VBA IDE by press
Alt+F11, Please select menu ->
References -> and select
EASendMailObj ActiveX Object,
click OK, the reference will be added to current VBA project, and you can start to use it to send email in your VBA project.
The following example codes demonstrate sending email with DomainKeys and DKIM signature.
In order to run it correctly, please change
recipient value to yours.
To get full sample projects, please download and install EASendMail on your machine.
Const ConnectNormal = 0 Const ConnectSSLAuto = 1 Const ConnectSTARTTLS = 2 Const ConnectDirectSSL = 3 Const ConnectTryTLS = 4 Private Sub btnSendMail_Click() Dim oSmtp As New EASendMailObjLib.Mail oSmtp.LicenseCode = "TryIt" ' Set your sender email address oSmtp.FromAddr = "firstname.lastname@example.org" ' Add recipient email address oSmtp.AddRecipientEx "email@example.com", 0 ' Set email subject oSmtp.Subject = "test email from VB 6.0 with DKIM signature" ' Set email body oSmtp.BodyText = "this is a test email sent from VB 6.0 project, do not reply" ' Your SMTP server address oSmtp.ServerAddr = "smtp.emailarchitect.net" ' User and password for ESMTP authentication, if your server doesn't require ' User authentication, please remove the following codes. oSmtp.UserName = "firstname.lastname@example.org" oSmtp.Password = "testpassword" ' ConnectTryTLS means if server supports SSL/TLS connection, SSL/TLS is used automatically oSmtp.ConnectType = ConnectTryTLS ' If your server uses 587 port ' oSmtp.ServerPort = 587 ' If your server uses 25/587/465 port with SSL/TLS ' oSmtp.ConnectType = ConnectSSLAuto ' oSmtp.ServerPort = 25 ' 25 or 587 or 465 ' Add DomainKeys and DKIM configuration file ' Then this email will be signed automatically oSmtp.AddHeader "X-DK-File", "c:\emailarchitectdomainkeys.txt" MsgBox "start to send email ..." If oSmtp.SendMail() = 0 Then MsgBox "email was sent successfully!" Else MsgBox "failed to send email with the following error:" & oSmtp.GetLastErrDescription() End If End Sub
If your SMTP server has implemented DKIM, you don’t have to sign DKIM in your codes, your email will be signed by your server automatically.
TLS is the successor of SSL, more and more SMTP servers require
TLS 1.2 encryption now.
If your operating system is
Windows XP/Vista/Windows 7/Windows 2003/2008/2008 R2/2012/2012 R2, you need to
enable TLS 1.2 protocol in your operating system like this:
Seperate builds of run-time dll for 32 and x64 platform
|Installation Path\Lib\native\x86\EASendMailObj.dll||32 bit|
|Installation Path\Lib\native\x64\EASendMailObj.dll||64 bit|
For VB6, C++, Delphi or other standard exe application, you can distribute EASendMailObj.dll with your application to target machine without COM-registration and installer. To learn more detail, please have a look at Registration-free COM with Manifest File.
For ASP, VBScript, VBA, MS SQL Stored Procedure, you need to install EASendMail on target machine by EASendMail installer, both 32bit/x64 DLL are installed and registered.