(VB.NET) Using Replace Patterns in Email

See more Email Object Examples

Demonstrates how to use the replace patterns (mail-merge) feature in Chilkat MailMan.

Chilkat .NET Downloads

Chilkat .NET Framework

Chilkat for .NET Core

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

Dim success As Boolean

' ---------------------------------------------------------------------
' Create an email template for sending.
Dim emailTemplate As New Chilkat.Email

' We're going to replace "FIRST_NAME" with an actual name.
' We arbitrarily chose "FIRST_NAME".  We can choose anything, such as "CUSTOMER_NAME" or "THE_RECIPIENT_NAME"...
emailTemplate.Subject = "Hello FIRST_NAME,"

emailTemplate.From = "john@example.com"
emailTemplate.AddTo("FIRST_NAME","RECIPIENT_EMAIL")

emailTemplate.SetHtmlBody("<html><body><h2>Hello FIRST_NAME,</h2><p>Your order for PRODUCT_NAME has been shipped.</p></body></html>")

' If the email is saved to a file, we can see what it contains:
emailTemplate.SaveEml("qa_output/emailTemplate.eml")

' For example:

' MIME-Version: 1.0
' Date: Tue, 26 Apr 2022 07:10:52 -0500
' Message-ID: <715CF231A9F07B0B9FDB073518CD94138D791866@XYZ>
' Content-Type: text/html; charset=us-ascii
' Content-Transfer-Encoding: 7bit
' X-Priority: 3 (Normal)
' Subject: Hello FIRST_NAME,
' From: john@example.com
' CKX-Bounce-Address: john@example.com
' To: FIRST_NAME <RECIPIENT_EMAIL>
' 
' <html><body><h2>Hello FIRST_NAME,</h2><p>Your order for PRODUCT_NAME has been shipped.</p></body></html>

' Note: Ignore the CKX-Bounce-Address header.  It is automatically removed by Chilkat prior to sending.
' All "CKX-" headers are automatically removed prior to sending.


' ---------------------------------------------------------------------
' Demonstrate replace patterns by setting and then rendering to MIME.

Dim mailman As New Chilkat.MailMan

emailTemplate.SetReplacePattern("FIRST_NAME","Elon")
emailTemplate.SetReplacePattern("RECIPIENT_EMAIL","elon.musk@example.com")
emailTemplate.SetReplacePattern("PRODUCT_NAME","Twitter Corporation")

' Render to MIME to see what we get.
' Note: When the MailMan sends an email, it renders the email to MIME and then sends.
' The rendering process is to do replacements, or possibly sign, encrypt, etc.
' When MailMan.SendEmail is called, internally the email is rendered, and the rendered email is sent.
' The equivalent to MailMan.Send email is to call email.RenderToMime followed by MailMan.SendMime.
Dim mime As String = mailman.RenderToMime(emailTemplate)
Debug.WriteLine(mime)

' This is the rendered MIME:

' MIME-Version: 1.0
' Date: Tue, 26 Apr 2022 07:25:49 -0500
' Message-ID: <750582BCDC891C67B48CEE2293C08B902C3891E9@XYZ>
' Content-Type: text/html; charset=us-ascii
' Content-Transfer-Encoding: 7bit
' X-Priority: 3 (Normal)
' Subject: Hello Elon,
' From: john@example.com
' To: Elon <elon.musk@example.com>
' 
' <html><body><h2>Hello Elon,</h2><p>Your order for Twitter Corporation has been shipped.</p></body></html>

' Note: When rendering, the Date and Message-ID headers are automatically regenerated.

' ---------------------------------------------------------------------
' An application can see what replacement patterns it previously set by calling SetReplacePattern multiple times.
Dim count As Integer = emailTemplate.NumReplacePatterns
Debug.WriteLine("Number of replace patterns: " & count)

Dim i As Integer = 0
While i < count
    ' Note: The GetReplaceString method was found to not be working correctly.  It was returning the same value as GetReplacePattern.
    ' It is fixed in Chilkat v9.5.0.91
    Debug.WriteLine(emailTemplate.GetReplacePattern(i) & ": " & emailTemplate.GetReplaceString(i))
    i = i + 1
End While

' Or lookup a replacement pattern by name:
Dim name As String = "FIRST_NAME"
Debug.WriteLine(name & " = " & emailTemplate.GetReplaceString2(name))

' Sample output:

' Number of replace patterns: 3
' FIRST_NAME: Elon
' RECIPIENT_EMAIL: elon.musk@example.com
' PRODUCT_NAME: Twitter Corporation
' FIRST_NAME = Elon

' ---------------------------------------------------------------------
' Finally... demonstrate sending emails using the replacement patterns.
' 

' Set our mail server settings..
mailman.SmtpHost = "smtp.mail.us-west-2.awsapps.com"
mailman.SmtpSsl = True
mailman.SmtpPort = 465

mailman.SmtpUsername = "john@example.com"
mailman.SmtpPassword = "the_password"


' Imagine we have data in JSON format, and we wish to send the templated email to each recipient...
' 

' {
' 	"mail_merge" : [
' 		{
' 			"to": "mary@example.com",
' 			"name": "Mary",
' 			"product": "Widget 1" 
' 		},
' 		{
' 			"to": "robert@example.com",
' 			"name": "Robert",
' 			"product": "Widget 2"
' 		}	
' 		...
' 	]
' }

Dim json As New Chilkat.JsonObject
success = json.LoadFile("qa_data/json/mail_merge.json")
If (success = False) Then
    Debug.WriteLine(json.LastErrorText)
    Exit Sub
End If


Dim emailAddr As String
Dim firstName As String
Dim product As String

i = 0
count = json.SizeOfArray("mail_merge")
While i < count
    json.I = i
    emailAddr = json.StringOf("mail_merge[i].to")
    firstName = json.StringOf("mail_merge[i].name")
    product = json.StringOf("mail_merge[i].product")

    emailTemplate.SetReplacePattern("FIRST_NAME",firstName)
    emailTemplate.SetReplacePattern("RECIPIENT_EMAIL",emailAddr)
    emailTemplate.SetReplacePattern("PRODUCT_NAME",product)


    success = mailman.SendEmail(emailTemplate)
    If (success = False) Then
        Debug.WriteLine(mailman.LastErrorText)
        Exit Sub
    End If


    Debug.WriteLine("Send email to " & emailAddr)

    i = i + 1
End While

Debug.WriteLine("Success.")