As part of the API changes made in the new Windows Phone 8.1 XAML programming model, the EmailComposeTask - and several other tasks - that were available in the Microsoft.Phone.Tasks namespace in Windows Phone 8 are no longer available.

Most of these have been replaced with a new way of performing the same tasks. For sending an email from within your app, the old way in Windows Phone 8 was as follows:


EmailComposeTask emailComposeTask = new EmailComposeTask();
emailComposeTask.Subject = "Subject";
emailComposeTask.To = "";

The new way in Windows Phone 8.1 to send an email from your app is as follows:
// Define Recipient
EmailRecipient sendTo = new EmailRecipient()
    Name = "Name of Recepient",
    Address = ""
// Create email object
EmailMessage mail = new EmailMessage();
mail.Subject = "this is the Subject";
mail.Body = "this is the Body";
// Add recipients to the mail object
// Open the share contract with Mail only:
await EmailManager.ShowComposeNewEmailAsync(mail);
Have fun,
Paras Wadehra
Microsoft MVP - Windows Platform Development
My WP Apps