Resource: Partial recreation of original headers data

src/Data/SMTP/Types/Resource.hs

@@ -110,3 +110,8 @@ originalData (PlainHeaders pp ss (psep, ssep)) =
   where
     catData :: [Header] -> BS.ByteString
     catData hh = BS.concat . map bare $ hh
+
+-- | Recreates the original resource text for the sealed headers only
+originalSealed :: PlainHeaders -> BS.ByteString
+originalSealed (PlainHeaders _ ss (_, ssep)) =
+  (BS.concat $ map bare ss) `BS.append` ssep