Send Templated Emails Using MailDefinition Object in ASP.Net

I recently found a better way to format my email messages in ASP.NET; using the MailDefinition object. Lets you use an email template and define tokens that you want to replace in it. This helps keep the presentation and business layers clean & separate and lets the designers go in and edit the email templates without having to navigate the StringBuilder. I think that any modern piece of software today, needs to send e-mail. Whether it being password recovery e-mails, rich reports, newsletters or anything else, being able to easily see and customize the look and feel of your e-mails is vital.

This article explains how to send email using ASP.NET. Yes, there are many other articles that cover sending email via .NET, I found that many articles suggest you create your HTML email using a string with the HTML markup in it. In this article we will look at a more detailed solution. One in which we use a regular HTML file as our template for the email. The template file will be a standard HTML file with the exception of some placeholders that we will use to populate our content and images right before we send the email. Think mail-merge in Microsoft Word. Finally, we will also learn how to send the email in such a way that if the email recipient's mail-client can't render HTML then they will get an alternate plain text version.

This is how it's done.

The following is the SendEmail method:

privatevoid SendEmail()


    Customer customer = CustomerData.GetCustomer(2);

   MailDefinition mailDefinition =new MailDefinition();

    mailDefinition.BodyFileName = "~/Email-Templates/Order-Confirmation.html";

    mailDefinition.From ="[email protected]";

    //Create a key-value collection of all the tokens you want to replace in your template...

    ListDictionary ldReplacements = new ListDictionary();

    ldReplacements.Add("<%FirstName%>", customer.FirstName);

    ldReplacements.Add("<%LastName%>", customer.LastName);

    ldReplacements.Add("<%Address1%>", customer.Address1);

    ldReplacements.Add("<%Address2%>", customer.Address2);

    ldReplacements.Add("<%City%>", customer.City);

    ldReplacements.Add("<%State%>", customer.State);

    ldReplacements.Add("<%Zip%>", customer.Zip);

    string mailTo = string.Format("{0} {1} <{2}>", customer.FirstName, customer.LastName, customer.EmailAddress);

    MailMessage mailMessage = mailDefinition.CreateMailMessage(mailTo, ldReplacements,this);

    mailMessage.From =new MailAddress("[email protected]","test site");

    mailMessage.IsBodyHtml = true;

    mailMessage.Subject ="Order Details";

    SmtpClient smtpClient = new SmtpClient(ConfigurationManager.AppSettings["SMTPServer"].ToString(), 25);



Your email template could be of any extension (txt, html, and so on) as long as its in a text format. I personally like to keep it in HTML format so that we can preview the email template in a browser. Basically it'll looks something like this:
Hello <%FirstName%> <%LastName%>,
Thank you for creating an account with us. Here are your details:
<%City%>, <%State%> <%Zip%>
Thank You,
My Site
Change the web.config file mail settings as  in the following  for setting mail host details:



         <smtpfrom="[email protected]">

             <networkhost="" =""/>    




The MailDefinition class can be used by controls to create a MailMessage object from a text file or a string that contains the body of the e-mail message. Use the MailDefinitionclass to simplify creating predefined e-mail messages to be sent by a control. If you want to send e-mail not using a control, see the System.Net.mail class.

You can make text substitutions in the body of the e-mail message by passing to the CreateMailMessage method an IDictionary instance that maps strings to their replacements.

Small Note :

The MailDefinition class does not support data binding. Properties of the MailDefinition class cannot be bound to data using the <%#   %> data-binding expression syntax.

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