<!-- Begin 
function emailCheck (emailStr) { 

/* The following variable tells the rest of the function whether or not 
to verify that the address ends in a two-letter country or well-known 
TLD.  1 means check it, 0 means don't. */ 

var checkTLD=1; 

/* The following is the list of known TLDs that an e-mail address must end with. */ 

var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/; 

/* The following pattern is used to check if the entered e-mail address 
fits the user@domain format.  It also is used to separate the username 
from the domain. */ 

var emailPat=/^(.+)@(.+)$/; 

/* The following string represents the pattern for matching all special 
characters.  We don't want to allow special characters in the address. 
These characters include ( ) < > @ , ; : \ " . [ ] */ 

var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]"; 

/* The following string represents the range of characters allowed in a 
username or domainname.  It really states which chars aren't allowed.*/ 

var validChars="\[^\\s" + specialChars + "\]"; 

/* The following pattern applies if the "user" is a quoted string (in 
which case, there are no rules about which characters are allowed 
and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com 
is a legal e-mail address. */ 

var quotedUser="(\"[^\"]*\")"; 

/* The following pattern applies for domains that are IP addresses, 
rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal 
e-mail address. NOTE: The square brackets are required. */ 

var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/; 

/* The following string represents an atom (basically a series of non-special characters.) */ 

var atom=validChars + '+'; 

/* The following string represents one word in the typical username. 
For example, in john.doe@somewhere.com, john and doe are words. 
Basically, a word is either an atom or quoted string. */ 

var word="(" + atom + "|" + quotedUser + ")"; 

// The following pattern describes the structure of the user 

var userPat=new RegExp("^" + word + "(\\." + word + ")*$"); 

/* The following pattern describes the structure of a normal symbolic 
domain, as opposed to ipDomainPat, shown above. */ 

var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$"); 

/* Finally, let's start trying to figure out if the supplied address is valid. */ 

/* Begin with the coarse pattern to simply break up user@domain into 
different pieces that are easy to analyze. */ 

var matchArray=emailStr.match(emailPat); 

if (matchArray==null) { 

/* Too many/few @'s or something; basically, this address doesn't 
even fit the general mould of a valid e-mail address. */ 

alert("Die E-Mail Adresse ist falsch.!"); 
return false; 
} 
var user=matchArray[1]; 
var domain=matchArray[2]; 

// Start by checking that only basic ASCII characters are in the strings (0-127). 

for (i=0; i<user.length; i++) { 
if (user.charCodeAt(i)>127) { 
alert("Ths username contains invalid characters."); 
return false; 
   } 
} 
for (i=0; i<domain.length; i++) { 
if (domain.charCodeAt(i)>127) { 
alert("Ths domain name contains invalid characters."); 
return false; 
   } 
} 

// See if "user" is valid 

if (user.match(userPat)==null) { 

// user is not valid 

alert("The username doesn't seem to be valid."); 
return false; 
} 

/* if the e-mail address is at an IP address (as opposed to a symbolic 
host name) make sure the IP address is valid. */ 

var IPArray=domain.match(ipDomainPat); 
if (IPArray!=null) { 

// this is an IP address 

for (var i=1;i<=4;i++) { 
if (IPArray[i]>255) { 
alert("Destination IP address is invalid!"); 
return false; 
   } 
} 
return true; 
} 

// Domain is symbolic name.  Check if it's valid. 

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 domain name does not seem to be valid."); 
return false; 
   } 
} 

/* domain name seems valid, but now make sure that it ends in a 
known top-level domain (like com, edu, gov) or a two-letter word, 
representing country (uk, nl), and that there's a hostname preceding 
the domain or country. */ 

if (checkTLD && domArr[domArr.length-1].length!=2 && 
domArr[domArr.length-1].search(knownDomsPat)==-1) { 
alert("Ihre Email-Adresse ist nicht korrekt." + ""); 
return false; 
} 

// Make sure there's a host name preceding the domain. 

if (len<2) { 
alert("Ihre Email-Adresse ist nicht korrekt."); 
return false; 
} 

// If we've gotten this far, everything's valid! 
return true; 
} 

//  End -->