폼메일이 발송이 안되네요.. 왜 그럴까요? 채택완료

</p><p><meta charset="utf-8"></p><p><?php</p><p>if(isset($_POST['telephone'])) {</p><p>     </p><p>    </p><p><span class="Apple-tab-span" style="white-space:pre">	</span>$email_to = "---@naver.com";</p><p><span class="Apple-tab-span" style="white-space:pre">	</span>$email_subject = "[폼메일] 견적의뢰 문의사항입니다.";</p><p><span class="Apple-tab-span" style="white-space:pre">	</span>$email_subject = '=?UTF-8?B?'.base64_encode($email_subject).'?=';</p><p> </p><p>     </p><p>     </p><p>    function died($error) {</p><p>        // your error code can go here</p><p>        echo "<script> alert('메일발송을 실패하였습니다.\\n이메일 및 연락처를 정확히 입력해주세요.');";</p><p><span class="Apple-tab-span" style="white-space:pre">		</span>echo "history.go(-1);";</p><p><span class="Apple-tab-span" style="white-space:pre">		</span>echo "</script>";</p><p>        die();</p><p>    }</p><p>     </p><p>    // validation expected data exists</p><p>    if( !isset($_POST['telephone'])) {</p><p>        died('We are sorry, but there appears to be a problem with the form you submitted.');       </p><p>    }</p><p>     </p><p>    $telephone = $_POST['telephone']; // not required</p><p>     </p><p>    $error_message = "";</p><p>    </p><p>  if(strlen($telephone) < 2) {</p><p>    $error_message .= 'The Comments you entered do not appear to be valid.
';</p><p>  }</p><p>  if(strlen($error_message) > 0) {</p><p>    died($error_message);</p><p>  }</p><p>    $email_message = "";</p><p>     </p><p>    function clean_string($string) {</p><p>      $bad = array("content-type","bcc:","to:","cc:","href");</p><p>      return str_replace($bad,"",$string);</p><p>    }</p><p>     </p><p>    $email_message .= "연락처 : ".clean_string($telephone)."\n\n";</p><p>     </p><p>     </p><p>// create email headers</p><p>$headers = 'From: '.$email_from;</p><p>// 제목이 깨질경우 아래 캐릭터셋 적용</p><p> </p><p>@mail($email_to, $email_subject, $email_message, $headers);  </p><p>?></p><p> </p><p><!-- include your own success html here --></p><p> </p><p><script></p><p>alert ("메일이 발송되었습니다.\n빠른 시일안에 답변드리겠습니다.");</p><p>location.href="<a href="<a href="http://---.com/" target="_blank" rel="noopener noreferrer">http://---.com/</a>"><a href="http://---.com/" target="_blank" rel="noopener noreferrer">http://---.com/</a></a>";</p><p></script></p><p> </p><p><?php</p><p>}</p><p>?></p><p>