That's incorrect. The validity of accepting the '+' character as part of an email address is part of the standard (-though it is a standard ignored by many prominent websites, aliexpress is just one example I believe)
The acceptibility of the '+' character is specified in RFC 5322 [1].
However, the behaviour where an address comprised of:
local-part "+" some-suffix "@" domain
is automatically routed to the address:
local-part "@" domain
it certainly not part of the standard. I find it very useful myself and would be displeased to see that functionality removed, yet this is certainly not part of the standard.
