[lolinder]

The parent's regular expression covers the most egregious typos without making any assumptions about domain names or tlds. If you wanted to help out with common typos you could add additional logic to specifically check for "*@gmial.com" or other permutations of the common domains. If you wanted to get really fancy, you could even run it by an edit distance function against the common domains and warn if they're close to a common one but not quite there.

Most typos, however, are likely to be in the first part, not in the domain. The only real way to validate against those is to try the address and see.

[eli]

It misses the very common mistake of typing a comma instead of a dot.

Otherwise, yeah, most people would be better served by a library that detects domain typos like https://github.com/mailcheck/mailcheck than spending time on regexes.