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	$Id: emailvalidate.js,v 1.1.1.1 2007/04/11 23:58:59 adsouza Exp $
	Description:	These functions find the position of an <A> tag in
					a document, so other elements can be positioned
					relative to it.

*/ 

function emailCheck( emailStr )
{

	// 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( "Email address appears invalid, confirm that @ and . exist." );
		return 0;

	}

	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." );
		return 0;
	
	}

	// 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 0;

			}
	
		}
	
		return true;
	
	}

	// Domain is symbolic name
	var domainArray		= domain.match( domainPat );

	if ( domainArray == null ) {
		alert( "The domain name doesn't seem to be valid." );
	    return 0;
	
	}

	// 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." );
		return 0;

	}

	// Make sure there's a host name preceding the domain.
	if ( len < 2 ) {
		var errStr	= "This address is missing a hostname!";
		alert( errStr );
		return 0;

	}

	// If we've gotten this far, everything's valid!
	return 1;

}