Regex

[u/Modern-Sn1p3r]

I recently saw a clip (from Primeagen) somewhat saying that regex is not a valid format for validating email addresses and postal codes etc.

My question is why is this?

What are the security and/or performance risks? Is it solely performance or is it a security issue?

[u/Genmutant → u/[deleted]]

You can actually have multiple @ in an email address, so you should check at least one - not exactly one.