[Setorrel]

Код:

stock ValidEmail(email[]) {
  new len=strlen(email);
  new cstate=0;
  new i;
  for(i=0;i<len;i++) {
    if ((cstate==0 || cstate==1) && (email[i]>='A' && email[i]<='Z') || (email[i]>='a' && email[i]<='z')  || (email[i]=='.')  || (email[i]=='-')  || (email[i]=='_'))
    {
    } else {
       // Ok no A..Z,a..z,_,.,-
       if ((cstate==0) &&(email[i]=='@')) {
          // its an @ after the name, ok state=1;
          cstate=1;
       } else {
          // Its stuff which is not allowed
          return false;
       }
    }
  }
  if (cstate<1) return false;
  if (len<6) return false;
  // A toplevel domain has only 3 to 4 signs :-)
  if ((email[len-3]=='.') || (email[len-4]=='.') || (email[len-5]=='.')) return true;
  return false;
}

Pareece que eso era lo que buscabas.