HTML formatted content in the description field of an iCalendar
By default, the iCalendar specification allows only plain text to be used in the description of an Event object.
X-ALT-DESC header
However Outlook can recognize HTML formatted content. This is supported using an additional field in the Event object called “X-ALT-DESC”, rather than the existing field:
DESCRIPTION:Reminder X-ALT-DESC;FMTTYPE=text/html:<!DOCTYPE HTML PUBLIC ""-//W3C//DTD HTML 3.2//E N""><HTML><BODY>\nhtml goes here\n</BODY></HTML>
Using Mail.dll you can set this field with no extra hassle:
// C# Appointment appointment = new Appointment(); Event e = appointment.AddEvent(); e.XAltDescription = @"<!DOCTYPE HTML PUBLIC ""-//W3C//DTD HTML 3.2//EN""><HTML><BODY> html goes here </BODY></HTML>";
' VB.NET Dim appointment As New Appointment() Dim e As [Event] = appointment.AddEvent() e.XAltDescription = "<!DOCTYPE HTML PUBLIC ""-//W3C//DTD HTML 3.2//EN""><HTML><BODY>" _ & vbCr & vbLf & "html goes here" _ & vbCr & vbLf & "</BODY></HTML>"
Adding custom headers
This is also good sample to show how to add a custom header to any PDI object:
// C#
Appointment appointment = new Appointment();
Event e = appointment.AddEvent();
const string html = @"<!DOCTYPE HTML PUBLIC ""-//W3C//DTD HTML 3.2//EN""><HTML><BODY>
html goes here
</BODY></HTML>";
PdiHeader header = new PdiHeader("X-ALT-DESC", html);
header.KeyParameters.Add(new KeyValues("FMTTYPE", "text/html"));
e.AddCustomHeader(header);
' VB.NET
Dim appointment As New Appointment()
Dim e As [Event] = appointment.AddEvent()
Const html As String = "<!DOCTYPE HTML PUBLIC ""-//W3C//DTD HTML 3.2//EN""><HTML><BODY>" _
& vbCr & vbLf & "html goes here" _
& vbCr & vbLf & "</BODY></HTML>"
Dim header As New PdiHeader("X-ALT-DESC", html)
header.KeyParameters.Add(New KeyValues("FMTTYPE", "text/html"))
e.AddCustomHeader(header)
ALTREP parameter
It is worth mentioning that RFC defines a way of specifying HTML content. The problem is that, it requires additional source (like email attachment or http address). Address of this resource, for example using “cid:” is set using ALTREP DESCRIPTION header:
DESCRIPTION;ALTREP="CID:part3.msg.970415T083000@example.com": Project XYZ Review Meeting will include the following agenda items: (a) Market Overview\, (b) Finances\, (c) Project Man agement
Mail.dll supports this feature also.
First we’ll define MIME object containing html data. Note that we are setting ContentId property.
// C# MimeText html = new MimeFactory().CreateMimeText(); html.ContentType = ContentType.TextHtml; html.Text = "<html><body>Html</body></html>"; html.ContentId = "part3.msg.970415T083000@example.com";
' VB.NET Dim html As MimeText = New MimeFactory().CreateMimeText() html.ContentType = ContentType.TextHtml html.Text = "<html><body>Html</body></html>" html.ContentId = "part3.msg.970415T083000@example.com"
Now we’ll create event:
// C# Appointment appointment = new Appointment(); Event e = appointment.AddEvent(); e.Description = "Project XYZ Review Meeting will include the following agenda items: (a) Market Overview, (b) Finances, (c) Project Management"; e.DescriptionAltRep = "CID:" + html.ContentId;
' VB.NET Dim appointment As New Appointment() Dim e As [Event] = appointment.AddEvent() e.Description = "Project XYZ Review Meeting will include the following agenda items: (a) Market Overview, (b) Finances, (c) Project Management" e.DescriptionAltRep = "CID:" + html.ContentId
Finally we need to create an email with the event and html data:
// C# MailBuilder builder = new MailBuilder(); builder.AddAttachment(html); builder.AddAppointment(appointment); IMail email = builder.Create();
' VB.NET Dim builder As New MailBuilder() builder.AddAttachment(html) builder.AddAppointment(appointment) Dim email As IMail = builder.Create()