I just finished reading "The First Five Pages" by Noah Lukeman and he encourages the aspiring writer to do just that -- spend the extra money and have the letter registered. He says it may tick off the agent or editor, but it will get the person's attention. Not a trick I would personally try, but I pity anyone who read this part of the book and went out and did just as Lukeman suggests...like this poor bloke did...
Yanno, I just don't get this advice.
Maybe he works in an office with people staffing the door from 9-5 but I don't. And a lot of my colleagues don't either.
When you send a registered letter, the recipient has to sign for it. That means ME. Not my intern, not my dogwalker, not Grandmother Snark, not the doorman. If I'm not here to sign for it I have to go to the post office and get it. Now, unlike the post offices in OtherPlace, America, the postal clerks HERE are New Yorkers. They don't take no guff from no one no how.
So after you stand in line for 10 minutes (minimum) you get to the window, hand over the pink slip and then, the clerk squints at you: "ID!". You haul out your PASSPORT cause you don't drive and don't have a license. Clerk looks at the passport photo, looks at you, looks again. "Names don't match". This is of course because you've addressed the query letter to the AGENCY name which may not be the agent's legal name anymore (witness protection sure, but marriage and other crimes can be involved). You bring out your business card. No dice.
More squinting. More consultation with supervisor. Time ticks by.
Well, you get the idea.
Now, when all these shenanigans are finished and you're actually clutching the letter, is it a notice from Shyster Snark that you've won eight gazillion dollars in the Poodle Sweepstakes? noooo..it's a damn query letter. Take it from me, you do NOT want me reading your query letter at this moment in time.
And even if I AM in the office when PostalPete comes a'calling, do you really think that sending a registered letter from YOUR ADDRESS means I'm going to be fooled into thinking it's something that needs my immediate attention. Only if you work for a law firm, used their letter head and envelope, and THEN I'm still going to open it and find..yes, it's a QUERY!!!
Query letters go in a pile in the order received. Sending it via registered mail only means you are an nitwit. I don't care what anyone else says, it's proof positive you're an nitwit if you believe them, and double proof if you do it.