I use this all the time, everywhere I can. The worst example of "we know what are valid email addresses better than anyone" case was when adidas.com decided th

I use this all the time, everywhere I can. The worst example of "we know what are valid email addresses better than anyone" case was when adidas.com decided that they'd redesign their registration flow and in the process disabled logins with "invalid" email addresses when they previously had accepted registrations and logins with email addresses tagged with + for years. That was genius.