> "^[[:alnum:].-_]+@[[:alnum:].-]+$"->regex
> str_match(emails, regex)
[,1]
[1,] "larry@gmail.com"
[2,] "larry-sally@sally.com"
[3,] "larry@sally.larry.com"
The @-sign is not in need of escaping in regex. And "." and "-" are not special in character classes. If you want to add a requirement for ".com",".co", ".edu", ".org" then you should specify how complete that list needs to be.
As pointed out by M42, this is not a surefire method. In fact it is claimed that there is no sure-fire method: Using a regular expression to validate an email address