//Email Validation
 function CheckEmail(emailStr, ControlId)
{
            if(emailStr !='')  //Check only when emailstr contains some text
            {
            activeId = ControlId;
            
		    /* The following pattern is used to check if the entered e-mail address
			fits the user@domain format.  It is also 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("Email address seems incorrect (check @ and .'s)")
				if (emailStr !='')
				    document.getElementById(activeId).focus();
				return false
				}
				
			var user=matchArray[1]
			var domain=matchArray[2]
			// See if "user" is valid 
			if (user.match(userPat)==null) {
			    // user is not valid
				alert("The username doesn't seem to be valid.")
				document.getElementById(activeId).focus();
				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!")
					document.getElementById(activeId).focus();
					return false
				}
			}
			return true
			}
			
			// Domain is symbolic name
			var domainArray=domain.match(domainPat)
			if (domainArray==null) {
				alert("The domain name doesn't seem to be valid.")
				document.getElementById(activeId).focus();
				return false
			}
			
			/* domain name seems valid, but now make sure that it ends in a
			three-letter word (like com, edu, gov) or a two-letter word,
			representing country (uk, nl), and that there's a hostname preceding 
			the domain or country. */
			/* Now we need to break up the domain to get a count of how many atoms
			it consists of. */
			var atomPat=new RegExp(atom,"g")
			var domArr=domain.match(atomPat)
			var len=domArr.length
			if (domArr[domArr.length-1].length<2 || 
				domArr[domArr.length-1].length>3) {
				// the address must end in a two letter or three letter word.
				alert("The address must end in a three-letter domain, or two letter country.")
				document.getElementById(activeId).focus();
				return false
			}
		
			// Make sure there's a host name preceding the domain.
			if (len<2) {
				var errStr="This address is missing a hostname!"
				alert(errStr)
				document.getElementById(activeId).focus();
				return false
			}
			
			// If we've gotten this far, everything's valid!
			return true;
		}
}