If you are getting ready to send out a manuscript (MS for one, MSS for plural) or have already sent one or more out in the past, you are likely aware of the high cost of mailing a document that can be an inch or more thick.
Writers are generally not known for having an excess of funds and the ink it took to print that manuscript alone was likely a bear. Add to that the fact that you may be printing out a dozen of these MSS and sending them out, the strain on your wallet is substantial.
So aside from just emailing those agents and editors who allow such an action, what do you do to reduce the costs? My suggestion is the possibility of Media Mail. It can be used effectively to send out a number of ‘educational materials’, but the nature of what is educational is fairly broad in most post offices. Most books are allowed, which may or may not include your carefully prepared MS.
The other limitations are that it not weigh more than 70lbs, cannot contain video games, advertizing, digital or computer drives and cannot have a length and girth in excess of 108 inches. Because anything listed media mail must be examined first, don’t close the package until after they agree that it is indeed qualified.
For the self-addressed stamped return envelope, you are probably going to have to make it first class mail even if they say the initial package is going to be media mail. The reason for this is two-fold.
First, the post office doing the return shipping may not agree and your editor or agent isn’t probably going to be happy if they get told you didn’t cover the proper postage. They might even just toss it in the trash instead. Second and most important, most of the people you will be sending the package to are going to simply seal up anything they return in whatever envelope you give and send it out as-is. Since the post office needs to look at an item before it counts as media mail, having it sealed means it is going to be instantly labeled first-class with the same consequences as above.
Check with your local post office. The worst that happens is they don’t agree that your MS is going to count as Media Mail. If they do, it significantly reduces the cost of shipping for you. Nothing ventured, nothing gained.