function emailCheck (emailStr) {
 var checkTLD=1;
 var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;
 var emailPat=/^(.+)@(.+)$/;
 var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";
 var validChars="\[^\\s" + specialChars + "\]";
 var quotedUser="(\"[^\"]*\")";
 var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
 var atom=validChars + '+';
 var word="(" + atom + "|" + quotedUser + ")";
 var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
 var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
 var matchArray=emailStr.match(emailPat);

if (matchArray==null) {
 alert("The email address is not correct (try with @ and .'s)");

 return false;
  }
 
 var user=matchArray[1];
 var domain=matchArray[2];

 for (i=0; i<user.length; i++) {
 
 if (user.charCodeAt(i)>127) {
 alert("The email address contain invalid characters.");

 return false;
  }
  }

 for (i=0; i<domain.length; i++) {
 if (domain.charCodeAt(i)>127) {
 alert("The domain of the email address contain invalid characters.");

 return false;
  }
  }

 if (user.match(userPat)==null) {
 alert("The email address is incorrect, please check it and try again.");

 return false;
  }

 var IPArray=domain.match(ipDomainPat);
 
 if (IPArray!=null) {
 for (var i=1;i<=4;i++) {
 if (IPArray[i]>255) {
 alert("The address IPInternet Protocol of destiny is incorrect!");

 return false;
  }
  }

 return true;
  }

 var atomPat=new RegExp("^" + atom + "$");
 var domArr=domain.split(".");
 var len=domArr.length;

 for (i=0;i<len;i++) {
 if (domArr[i].search(atomPat)==-1) {
 alert("The email address is incorrect, please check it, including the incorrect use of signos de puntuación, comas , o puntos [.] at the end of the adrress.");

 return false;
  }
  }

 if (checkTLD && domArr[domArr.length-1].length!=2 &&
 domArr[domArr.length-1].search(knownDomsPat)==-1) {
 alert("The email address must end in a domain or two letters " + "country.");

 return false;
  }

 if (len<2) {
 alert("Is necesary the host name in your email address - check it. Or maybe you add an white space at the end of the address - fix the error and try again.");

 return false;
  }

 return true;
  }