Looking for a character that is allowed in Filenames but not allowed in email addresses... Any clue?

Question

I am trying to create multiple html files that are associated with an email address. But since the "@" cannot be used in filenames, and in order to avoid confusion, I am trying to replace it with a character that won't normally exist in an email address.

Anything comes in mind?

Thanks!

Answer 1

Comma and semi-colon is not allowed in email address but in filenames on most file systems.