public IEnumerable<String> ToText(Boolean IncludeHeaders = true)
{
var AllHeaders = (IncludeHeaders
? MailHeaders.
Select(v => v.Key + ": " + v.Value).
Concat(new String[] { "" })
: new String[0]).
Concat(_MailBody != null ? _MailBody : (IEnumerable<String>) new String[0]).
Concat(_NestedBodyparts.
SelectMany(bodypart => new String[] { "--" + ContentType.MIMEBoundary }.
Concat(bodypart.ToText(true)))).
Concat(_NestedBodyparts.Count() > 0 ? new String[] { "--" + ContentType.MIMEBoundary + "--" } : new String[0]);
return AllHeaders;
}