I think your question is whether a person using a Korean keyboard would be able to type your e-mail address or not. Well, in order to comply with international standards, e-mail addresses can only consist of the following characters:
http://en.wikipedia.org/wiki/E-mail_address wrote:The local-part of the e-mail address may use any of these ASCII characters:
* Uppercase and lowercase English letters (a-z, A-Z)
* Digits 0 through 9
* Characters ! # $ % & ' * + - / = ? ^ _ ` { | } ~
* Character . provided that it is not the first nor last character, nor may it appear two or more times consecutively.
That means that no e-mail addresses use Korean characters anyway, so the person in question would be completely comfortable typing in an e-mail address using English characters.
In fact, Korean keyboards have a key that switches the typing mode to a basically normal QWERTY keyboard layout for just this sort of situation.