Deleted e-mail adress

I have one question. My master account is linked to an e-mail address that is deleted. I can play Guild Wars but if i brought Mercenary Hero Pack will i be able to register it?

Stuff you buy from the online store is automatically added to your account. So yes - you will be able to play.

The "e-mail" address you log in with is just the "account name". It has nothing to do with actual e-mail or logging in to any e-mail account. One thing to be aware of though, is that unless you have a valid "contact" e-mail associated with your account, any e-mail correspondence from GW, such as a password change, will be sent to the e-mail address used as the account name. You should link a valid e-mail ASAP.

"Registering" your Mercenary Heroes, and the characters who will use them, is only a matter of talking to an NPC. It doesn't involve e-mail.

Quaker is right, it's just an account name. NCSoft or ArenaNet will never send email to that address, they will use the email you currently registered.