Hello guys PHP is a new language for me. I had created a simple form which sends information to user via mail for this i m using mail() function But its showing me error. The error show following message Warning: mail(): SMTP server response: 550 5.7.1 Unable to relay for rajesh@softcellsolutions.com in C:\PHP\inquiry.php on line 40 Please help me to sort it out. Here is the code :- [b]FORM.HTML[/b] <html> <head> <title>My Form</title> </head> <body> <div align="center"><font color="red"><H1>INQUIRY FORM</H1></font></div> <form action="inquiry.php" method="post"> <b>What is your Name:</b><input type="text" name="name"><br> <b>Sex:</b> Male<input type="radio" name="sex" value="male"> Female<input type="radio" name="sex" value="female"><br> <b>Age:</b><input type="text" name="age" size="2"><br> <b>Select your Favorite Game:</b> <select name="game" > <option>Cricket</option> <option>Football</option> <option>Hockey</option> <option>Basket Ball</option> <option>Tenis</option> </select><br> <b>Your Mail ID:</b><input type="text" name="mail"><br> <input type="submit" value="SUBMIT"> </form> </body> </html> INQUIRY.PHP <?php $error=array(); if(empty($name)) $error[]="Please enter a name"; if(!isset($sex)) $error[]="Please select your sex"; if(!isset($game)) $error[]="Please select a game"; if(empty($age)) $error[]="Please enter your age"; if(empty($mail)) $error[]="Please enter your email id"; $numerr=count($error); if($numerr>0) { print("<font color=#F24A2D><h1>There is An error Occured in Entering Data !!!!!!</h1></font>"); for($i=0;$i<$numerr;$i++) print("<li>".$error[$i]."</li><br>"); print("<b>Please go<a href=form.html> back</a> and complete your form</b>"); exit; } $n=ucfirst($name); print("<div align=center><font color=#8B4396><h1>$n Your entered information is:</h1></font></div>"); print("Your Name is:".$name."<br>"); print("Your Sex is:".$sex."<br>"); print("Your Age is:".$age."<br>"); print("Your Favorite Game:".$game."<br>"); print("Your mail ID:".$mail."<br>"); $header="From:cool_rajesh1783@yahoo.com"; $comment="hi"; mail($mail,$name,$comment,$header); ?>