Town Crier – An open-source e-mail templating engine for .NET

In medieval times, town criers were the primary means of making announcements to a community. Nowadays a man with a bell is a very imaginative – but not particularly practical – means of communication.

One common scenario, especially in the business world, is the need to send out an email to a large number of people. Of course a big anonymous email lacks the friendliness of the local loud-mouthed peasant and so we try to personalise the emails with individuals’ names etc.

I suspect most .NET developers have come across this problem at some point in their career. This generally leads to a lot of messy string concatenation and trying to manhandle the System.Net.Mail.SmtpClient into doing what you want. With text-based emails this is ugly, when HTML is involved it becomes a world of pain.

Town Crier is a project I have been working on to simplify this scenario. The basic workflow for sending a templated e-mail is as follows:

1. Create an email template.
   This can be either a plain-text or HTML file (or both). Tokens to be replaced are written like this: {%= customersname %}

   Sample email templates:
   
   

2. Write some very simple code in the CLR language of your choice, in this case C#:

   var factory = new MergedEmailFactory(new TemplateParser());
   
   var tokenValues = new Dictionary<string, string>
                         {
                             {"name", "Joe Bloggs"},
                             {"age", "21"}
                         };
   
   MailMessage message = factory
       .WithTokenValues(tokenValues)
       .WithSubject("Test Subject")
       .WithHtmlBodyFromFile(@"templates\sample-email.html")
       .WithPlainTextBodyFromFile(@"templates\sample-email.txt")
       .Create();
   
   var from = new MailAddress("sender@test.com", "Automated Emailer");
   var to = new MailAddress("recipient@test.com", "Joe Bloggs");
   message.From = from;
   message.To.Add(to);
   
   var smtpClient = new SmtpClient();
   smtpClient.Send(message);
   

   Of course it’s then trivial to loop through rows in a database, populate the dictionary and perform a “mail-merge” programatically.

   One final handy tip – there is included a handy extension method to allow you to save the message to a .eml file:

   message.Save(new FileStream(@"output.eml", FileMode.CreateNew));

That’s pretty much it! It’s fairly basic but I’ve found it to be very useful. It’s also my first open-source project so please be nice!

I am releasing it under the Lesser GNU Public Licence. Go grab the sources at GitHub.