function IsMail(mail)
{
   var pos, pos2, l = mail.length;
   if( l <= 5 ) return true;
   else if( mail.indexOf( '@', 0 ) < 2 ) return true;
	else
	{
	   pos = mail.indexOf( '@', 0 );
	   if( mail.indexOf( '.', pos ) - pos < 2 ) return true;
	   else if( l - mail.lastIndexOf( '.' ) < 3 ) return true;
		   else if ( ( mail.lastIndexOf( '.' ) + 2 ) > l || ( mail.lastIndexOf( '.' ) + 5 ) < l ) return true;
		else 
		{
		   var invalidChars=new Array("~","!","#","$","%","^","&","*","(",")","+","=","[","]",":",";",",","\"","'","|","{","}","\\","/","<",">","?", " " ),len=invalidChars.length,tmp=mail.split("");
		   for( var x = 0; x < l; x++ )
			for(var j = 0; j < len; j++ )
				if( tmp[x] == invalidChars[j] )	return true;

		   return false;
		}
	}
}