I've switched to doing everything by email. Maybe I shouldn't?

Folders, boxes, and other fancy presentations just increase the handling time for any proposal, which annoys the publisher.

It's not tacky, it's what they prefer.

Hold the proposal together with a paper clip. If the sample chapters are beefy, you might use one of those small metal spring clips that can grab onto a half-inch stack of paper. But that's about it.

No decent editor would be annoyed by a folder to the point where it would cause her to turn back an otherwise brilliant proposal--but you never want to submit something that looks slick or cute. THAT'S tacky. Keep in mind also that the most elegant or attractive presentation won't save a mediocre proposal.

I wouldn't submit anything electronically unless I had cleared it with the editor beforehand. Hard copy is easier on the eyes. And always, always, double space.

Too many new writers focus on superficial ways to make their work stand out from the slush pile. If you want to impress an editor, write a well-thought-out proposal that convinces her you indeed have a good idea for a book, and that you have the qualifications to write it. Few enough would-be writers can manage that.

This is certainly a surprise to me, and I hope that I haven't ended in the slush because of any presentation goofs. I suspect that I was under the impression that report folders were a standard way to present anything from a hi school report/business report or any group of papers. It keeps things clean, flat and dry.
I have never sent anything electronically, but I have approached editors, that I have been given an introduction to. In these cases I introduce myself by email and paste (not attach) the book outline and from that, if they want the full proposal I send it on. Although everthing in the proposal is printed double spaced, I do not include all the pictures - they take ages to print out and look flat. I send a copy of the images and the whole proposal on a disk which I send along with the full proposal.
As the current proposal is too think for those 1/4" spine things, it is great to know that I will be conforming to the norm, rather than committing faux pas.

Like much in life 'it all depends'. Smaller regional magazines aren't swamped with material and the editors (probably 'a' editor) has lots of time to open an envelope. I've written for two regional gardening magazines and they actively pursue 'quality' articles rather than are swamped by material.
One can write a letter, email, telephone but 'put your name' out there so the editor knows who you are. It's much, much easier to get published in a larger national circulation magazine if you have material published in smaller circulation magazines...you are a proven commodity and the editor can see the quality of the writing, photos, etc first hand.

Always send a proposal to a national magazine with samples of your published articles. I wouldn't worry about the type of envelope, etc. Just make sure it is done professionally. submitting your actual article will be according to the editor's guidelines after you have a nod of approval. It takes 5 minutes to pick up the phone and ask.