As part of the checkout process at Old Navy, I ask customers for their e-mail address so the company can send them coupons and promotions.
The whole process of giving someone your e-mail address is tricky, because they can be spelled many different ways and you have to make sure you're conveying it in a way that makes sense.
But most people seem to have worked out the best way to successfully convey their e-mail address.
Sometimes it's best to spell the whole thing, like if it's just gibberish letters and numbers (initials, birthdays, etc). Sometimes you have to spell part of it and say part of it, like if it's your first and last name and you have a simple first name and a complicated last name. Sometimes you don't need to spell it at all, like if you have a simple name or it's words that make sense, like "mommyofthree" or something.
My e-mail address is firstname.lastname@example.org. When I give this to people, I say "Skaggs, S-K-A-G-G-S, K-R at gmail." I do this because nobody up here knows how to spell Skaggs, but it's awkward to spell out that many letters without prefacing it with the word you're going to be spelling.
Most people have this figured out, but sometimes people are bad at it.
With names, the best way is to say it and then indicate if there's something weird about it. So if your name is Kristin, you can say "Kristin with an I, not an E" instead of spelling out "K-R-I-S-T-I-N."
This woman yesterday spelled out the longest e-mail address ever, and both her first name and her last name were spelled the most normal way possible. You don't need to spell out Cindy if it's spelled like that. I don't remember her last name, but it was a compound word and both of the words were spelled like the normal word, so that also didn't need to be spelled out.
Don't spell everything out! It prolongs the e-mail process!