Read, Create, and Edit Outlook Email Templates (OFT) in C#

ConvertingMsgToOft.cs

var msg = MapiMessage.Load("input.msg");

msg.Save("template.oft", SaveOptions.DefaultOft);

GeneralFileTypeDetection.cs

FileFormatInfo info = FileFormatUtil.DetectFileFormat("input.msg");

if (info.FileFormatType == FileFormatType.Oft)
{
    Console.WriteLine("This is an Outlook Template file.");
}

LoadingAndModifyingOftFiles.cs

var template = MapiMessage.Load("template.oft");

template.Subject = "Updated Subject Line";
template.Body = "This is an updated body text.";
template.Recipients.Add("[email protected]");

template.Save("updated_template.oft", SaveOptions.DefaultOft);

SavingEmFileAsOutlookTemplate.cs

var eml = MailMessage.Load("input.eml");

eml.Save("template_from_eml.oft", SaveOptions.DefaultOft);

TemplateCheckAfterLoading.cs

var msg = MapiMessage.Load("input.msg");

if (msg.IsTemplate)
{
    Console.WriteLine("The message is an Outlook Template.");
}

UseExplicitSaveOptions1.cs

var saveOptions = new MsgSaveOptions(MailMessageSaveType.OutlookTemplateFormat);
msg.Save("template_alt1.oft", saveOptions);

UseExplicitSaveOptions2.cs

saveOptions = SaveOptions.CreateSaveOptions(MailMessageSaveType.OutlookTemplateFormat);
msg.Save("template_alt2.oft", saveOptions);

UsingSaveOptionsExplicitly.cs

var saveOptions = new MsgSaveOptions(MailMessageSaveType.OutlookTemplateFormat);
eml.Save("template_alt1.oft", saveOptions);

saveOptions = SaveOptions.CreateSaveOptions(MailMessageSaveType.OutlookTemplateFormat);
eml.Save("template_alt2.oft", saveOptions);