Of course the only way to be 100% sure would be to actually test it out by sending an actual email isn't it. This is just so obvious. I think the point of email

Of course the only way to be 100% sure would be to actually test it out by sending an actual email isn't it. This is just so obvious. I think the point of email regexes out there is not to make up for the user's silly typing mistake. It's just more to reject nonsensical/malicious/blatantly false inputs etc. as the first layer of protection really, and nobody would really spend tons of time on crafting a "perfect" regex anyways I'm pretty sure, so that's never been a problem at all.