"Creative work must meet a basic level of originality to be considered the product of an author. Direct copies of someone else’s work can’t be copyrighted, and neither can facts, short phrases, titles, etc. For example, the names and addresses in a phonebook can’t be copyrighted but the photo on its front cover most certainly can."
https://www.newmediarights.org/business_models/artist/ii_wha...
Also, even if you could copyright your password, copyright protects against unauthorized distribution. If Google is merely storing your password, it's not distributing it.
(A single word or phrase, e.g., "Google", can be trademarked, but that specifically involves its use in commerce to identify a brand. But it can't be copyrighted.)
That's not why it's excluded from copyright.
> If the actual email name is allocated (by the email provider)then I most certainly do not hold the copyright (the email provider does).
No, the email provider doesn't hold the copyright on email addresses, because those aren't copyrightable either.