private static void FormatMimeEntity(StringBuilder stringBuilder, MimeEntity entity, string indent) { stringBuilder.AppendLine($"{indent}Mime Type: {entity.ContentType.MimeType}"); indent += Indent; if (entity is Multipart multipart) { foreach (var subentity in multipart) { FormatMimeEntity(stringBuilder, subentity, indent); } } else if (entity is TextPart textPart) { var text = string.Join('\n', textPart.Text.Split("\n").Select(line => $"{indent}{line}")); stringBuilder.AppendLine(text); } else if (entity is MimePart mimePart) { stringBuilder.AppendLine($"{indent}Attachment: {mimePart.FileName}"); } else { stringBuilder.AppendLine($"{indent}Unhandled type {entity.GetType()}"); } }