private void SetPostmarkMeta(RestBase request)
{
request.AddHeader("Accept", "application/json");
request.AddHeader("Content-Type", "application/json; charset=utf-8");
request.AddHeader("X-Postmark-Server-Token", ServerToken);
request.AddHeader("User-Agent", "Postmark.NET 1.x (" + this.GetType().AssemblyQualifiedName + ")");
}