Dear Miss Snark,
Having read your brilliant separated (huh?-spell czech strikes a hen) for some time as a resource for infinite literary wisdom, I now come to you with a most pressing dilemma.
I have been working for some time now on a book that I intended to be part of a series of three books. However, after reading about how unlikely it was to get an agent if I say that the book I'm sending is part of a series, and after realising that the first book is going to be much shorter than I intended, I decided to make the series into one book separated into three parts. If you received a partial that had "Part One" in front of "Chapter One", would you immeadiatly remove the offending material from your presence? Crush it under you stilletos? Would it be a hindrance to have a novel in parts when querying a novel, or is this just a nitwitty question?
Think about this for a second. Why would you send a page that says "part one" and another page saying Chapter One if you're sending only a partial?
I'm AMAZED at the stuff people send as part of a query letter or first three chapters/fifty pages: tables of contents, acknowledgment pages, dedication pages, little poems, "Part one".
All I care about right now is the writing. That's it. If you have great fresh fabulous and interesting writing, you can have a Partridge in a pear tree section and I won't care.
If someone asks to read the entire novel, then you include the designations that make it easier to read. That means ok for "Part one" and so on. Other than that, save it.