Spellutils is a suite of programs which are used to isolate some parts from various types of files and hand them over to another program which may change the texts; it is typically a spell checker. Afterwards the possibly changed text parts are copied back in place in the original file.
The newsbody program is intended for use on mail and news messages; it can e.g. ignore headers, quoted material and signatures.
The pospell program is for use on translated strings in .po files.