/^[-w.%+]{1,64}@(?:[A-Z0-9-]{1,63}.){1,125}[A-Z]{2,63}$/i

abcde.fghi@gmail.com
nombre-apellido@do-mi-nio.info

germán@bla.com
yo@mi-compañía.com
estação@brasil.com.br

/^(([^<>()[].,;:s@"]+(.[^<>()[].,;:s@"]+)*)|(".+"))@(([^<>()[].,;:s@"]+.)+[^<>()[].,;:s@"]{2,})$/i

> emailRegex.test("abcde.fghi@gmail.com");
< true
> emailRegex.test("germán@bla.com");
< true

/^(?:[^<>()[].,;:s@"]+(.[^<>()[].,;:s@"]+)*|"[^n"]+")@(?:[^<>()[].,;:s@"]+.)+[^<>()[].,;:s@"]{2,63}$/i

червь.ca®rton@picnic.com

josé.patroñinio@hotdog.com

function validarEmail(valor) {
  if (/^(([^<>()[].,;:s@"]+(.[^<>()[].,;:s@"]+)*)|(".+"))@(([^<>()[].,;:s@"]+.)+[^<>()[].,;:s@"]{2,})$/i.test(valor)){
   alert("La dirección de email " + valor + " es correcta!.");
  } else {
   alert("La dirección de email es incorrecta!.");
  }
}

validarEmail("jorgésys.boc+al@hotflow.com");

Abc@example.com                                (English, ASCII)
  Abc.123@example.com                            (English, ASCII)
  user+mailbox/department=shipping@example.com   (English, ASCII)
  !#$%&'*+-/=?^_`.{|}~@example.com               (English, ASCII)
  "Abc@def"@example.com                          (English, ASCII)
  "Fred Bloggs"@example.com                      (English, ASCII)
  "Joe.\Blow"@example.com                       (English, ASCII)

用户@例子.广告                   (Chinese, Unicode)
  अजय@डाटा.भारत                    (Hindi, Unicode)
  квіточка@пошта.укр             (Ukrainian, Unicode)
  θσερ@εχαμπλε.ψομ               (Greek, Unicode)
  Dörte@Sörensen.example.com     (German, Unicode)
  аджай@экзампл.рус              (Russian, Unicode)

A[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?z

/^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/

/[A-Za-zu0021-u007Fu00C0-u00D6u00D8-u00f6u00f8-u00ff]+/g

^([^x00-x20x22x28x29x2cx2ex3a-x3cx3ex40x5b-x5dx7f-xff]+|x22([^x0dx22x5cx80-xff]|x5c[x00-x7f])*x22)(x2e([^x00-x20x22x28x29x2cx2ex3a-x3cx3ex40x5b-x5dx7f-xff]+|x22([^x0dx22x5cx80-xff]|x5c[x00-x7f])*x22))*x40([^x00-x20x22x28x29x2cx2ex3a-x3cx3ex40x5b-x5dx7f-xff]+|x5b([^x0dx5b-x5dx80-xff]|x5c[x00-x7f])*x5d)(x2e([^x00-x20x22x28x29x2cx2ex3a-x3cx3ex40x5b-x5dx7f-xff]+|x5b([^x0dx5b-x5dx80-xff]|x5c[x00-x7f])*x5d))*$