Nope, there is no restriction for plus addresses. I validate email addresses and specifically allow + and . in the part before the @ sign. myemail+1@mydomain.com and myemail+2@mydomain.com will be considered two different users.
Have to add also that the "plus feature" isn't a Gmail-specific invention but a standardized way of referring to the same mailbox using different addresses. But some email providers don't support this feature, and many input validators out on the Internet don't either.
Have to add also that the "plus feature" isn't a Gmail-specific invention but a standardized way of referring to the same mailbox using different addresses. But some email providers don't support this feature, and many input validators out on the Internet don't either.