There are many regexes that validate email, and they usually aren’t compliant with the RFC, there are some details in the very old answer on SO. So, better not validate and just send a confirmation, than restrict and lock people out, imo
The article you just mentioned in the comments includes both a completely reasonable and viable regex and binary and library alternatives that are in most languages.
There is some danger that common usage and widespread sloppy coding will establish a de facto standard for e-mail addresses that is more restrictive than the recorded formal standard.
There are many regexes that validate email, and they usually aren’t compliant with the RFC, there are some details in the very old answer on SO. So, better not validate and just send a confirmation, than restrict and lock people out, imo
The article you just mentioned in the comments includes both a completely reasonable and viable regex and binary and library alternatives that are in most languages.
Reasonable and viable ≠ RFC compliant
This quote summarises my views: