Validation to avoid mistakes is, as they point out, good. I'd even go so far as to extend it so that I reject those without any tld (without any dots) just bec

Validation to avoid mistakes is, as they point out, good. I'd even go so far as to extend it so that I reject those without any tld (without any dots) just because it's 99.999% a mistake and I don't care about the person who has ben@net. I'd also reject ip numbers. Next is the spicy take: I need to consider WHY I am gathering this email? If I'm gathering it for "marketing purposes" or any such cross correlation to other systems, then I'd also reject bob.smith+dontspamme@gmail.com. Or I'd keep both so you can do cross referencing on both the + address and the "raw" one.