Zed's E-mail: My Good Ol' Uncle Sugar

Question

My friend Gabby and I constantly look out for each other. Just the other day, she received a strange message from what I thought was an uncle of hers. "Problem is," she started with a worried look, "I don't even have an Uncle Sugar! Do you think someone is trying to scam me?" I tried my best to assuage her, then I looked at the email, which read as such:

FROM: uncle_sugar@navientlogin.net
TO: 4n0gr4mm4G4bby@programmingant.com
-------------------------------------
Dear Gabby,

DV ECW is it HP make ZPG with an PSC?

Kindly,
    Uncle Sugar

I had to blink twice at first; it couldn't be! I quickly made a note of what the message said, and started humming away as I began decrypting the message a second time, but I noticed something odd... it seemed familiar. I began muttering to myself --- this, of course, did little to help my friend who was in a near-panicked state as-is:

• "Of all musical instruments, why a..."
• "Hmm, that isn't how you spell... perhaps they meant the other one?"
• "Well, wait, perhaps they meant to add an '×'? That would make it..."

Eureka! I had figured it out; I just had to take just one last look at the sender, and it all made perfect sense! Gabby was hysterical at this point: "Well, what does it say?! Is it a death threat?!? Are they trying to hurt me?!"

---

"Quite the contrary," I reassured my friend. "After all, it was a friendly message... How easy it was, indeed!"

How could I have possibly figured this all out? Maybe you can explain why?

While asking for an explanation sounds vague at first, there is only one possible way to come to my conclusion. The challenge, then, is to decipher the message into plaintext just like I did.

---

HINTS:

Naturally, Gabby wasn't amused by my jest (really, I was only trying to help), so she confronted this "uncle of hers" with a message of her own. She was surprised to see a new message pop up not too soon after, which read:

Ahasuerus' many suitors gave him many names, but none would
know him by his less-common moniker, BOUNB. And wouldn't you
know it, he was even British at one time! Yes, yes, I know;
I laughed, too! But perhaps it's best you don't say his name
out loud... his name is not so easily understood in the open
air.

Even I scratched my head at this one, but rest assured, everything he said was true!

Gabby was determined; she wanted to figure out this faceless perpetrator's identity at all costs. I kept telling her not to worry so much about it, reminding her yet again that her "uncle" was really just an affable stranger, but Gabby already had her mind made up. She sent another message with fervor, but this time the response took a while. When it finally came, however, this is what we saw:

I have here a list of relatives you should know about.

Y'see, there's 
our great-cousin Charlie,
"Easy" Ed (he doesn't like being called 'Edward'),
George Gee
"Monkey" Mike and his sister Emma,
our nutty Nan,
Robert — although, now, everybody calls him Roger,
and, of course,
my ol' drinking buddy, Willie — you remember William, don't you?

Gabby had that worried look on her again; "I don't remember any of these people. Do you?" I chuckled because I knew them all — and so should everyone else.