are e-mail addresses "capital" letter sensitive?

I've been expecting to hear from someone since yesterday.
I decided to view their website and there was a link to send an e-mail.
Well, I had their business card and it was an aol.com address. The user name was 3 words, so 3 words at aol.com. The middle word on the business card was in capital letters.
I sent the e-mail from my Hotmail address. Hours go by and no reply,
This person stands to earn a commission for their help on some real estate so I went to my "sent" box to read over the message I sent them.
The "to" box, shows the 3 words but none of the letters are capitalized.
So, I go back to the website and there is a link to send an e-mail. The address shown there is the same three words at aol.com and the first letter in each word is capitallized.

I can not be a pest by calling this person, so I want to know if my e-mail sent to:
wordWORDword@aol.com got delivered, though when I look at my message in my Hotmail "sent folder" it shows that my message went to wordwordword@aol.com.

Are e-maail addresses capital letter sensitive?

I would guess no, since the business card says:
wordWORDword@aol.com
and the website says
WordWordWord@aol.com
and they are the same 3 words, so it seems illogical to have multiple e-mail addresses all with varying capital letters.

I happen to be on a computer which has Windows Mail but I'm not logged in for e-mail and can not. When I clicked on the e-mail address on the person's website, of course Vista tried to open Windows Mail. And though I can not send an e-mail from there, it has the "new message" box open and has the e-mail addres in the box and it is:
WordWordWord@aol.com which matches "exactly" what the website says.

When I sent my message to wordWORDword@aol.com from my hotmail address, why does the sent copy show that the destination was wordwordword@aol.com?