I think "traditional" is more appropriate than "standard" (see International email ).

sed is used for simple search and replace, and in most cases, it is just used to remove/replace a part of a line after a certain char. I suggest you re-consider the requirements and come up with a more concrete problem statement than "matching emails with POSIX regex".

@wiktor.stribizew‭ hello, I misunderstand the last part of your comment; I very much agree that sed is used (or should be used) for simple match and replace operations as you have described but because I didn't mention POSIX regex at all in my question I can say that my original goal here was to match quite simple email patterns...

sed only supports POSIX regex flavor. What I mean is you do not need any super-complex regex in case you want to replace an email address in a E-mail: aaa@bbb.com string (a line in a file) since you may just use sed "s/E-mail: .*/E-mail: ${new_email_address}/" file. Matching arbitrary emails is next to impossible with a "simple" email pattern. If you mean some specific format, you should explain this format in the question.