试试这个

if ($_POST['submit']) {
    $success= mail($to, $subject, $body, $from);
    if($success)
    { 
        echo '
        <p>Your message has been sent!</p>
        ';
    } else { 
        echo '
        <p>Something went wrong, go back and try again!</p>
        '; 
    }
}

如果使用PHP发送邮件遇到问题，可以考虑使用PHPMailer或SwiftMailer等替代方案。

当我需要用PHP发送邮件时，我通常使用SwiftMailer。

基本用法:

require 'mail/swift_required.php';

$message = Swift_Message::newInstance()
    // The subject of your email
    ->setSubject('Jane Doe sends you a message')
    // The from address(es)
    ->setFrom(array('jane.doe@gmail.com' => 'Jane Doe'))
    // The to address(es)
    ->setTo(array('frank.stevens@gmail.com' => 'Frank Stevens'))
    // Here, you put the content of your email
    ->setBody('<h3>New message</h3><p>Here goes the rest of my message</p>', 'text/html');

if (Swift_Mailer::newInstance(Swift_MailTransport::newInstance())->send($message)) {
    echo json_encode([
        "status" => "OK",
        "message" => 'Your message has been sent!'
    ], JSON_PRETTY_PRINT);
} else {
    echo json_encode([
        "status" => "error",
        "message" => 'Oops! Something went wrong!'
    ], JSON_PRETTY_PRINT);
}

有关如何使用SwiftMailer的更多信息，请参阅官方文档。

如果您正在使用SMTP配置来发送电子邮件，请尝试使用PHPMailer。您可以从https://github.com/PHPMailer/PHPMailer下载该库。

我用这种方式创建了我的电子邮件:

function send_mail($email, $recipient_name, $message='')
{
    require("phpmailer/class.phpmailer.php");

    $mail = new PHPMailer();

    $mail->CharSet = "utf-8";
    $mail->IsSMTP();                                      // Set mailer to use SMTP
    $mail->Host = "mail.example.com";  // Specify main and backup server
    $mail->SMTPAuth = true;     // Turn on SMTP authentication
    $mail->Username = "myusername";  // SMTP username
    $mail->Password = "p@ssw0rd"; // SMTP password

    $mail->From = "me@walalang.com";
    $mail->FromName = "System-Ad";
    $mail->AddAddress($email, $recipient_name);

    $mail->WordWrap = 50;                                 // Set word wrap to 50 characters
    $mail->IsHTML(true);                                  // Set email format to HTML (true) or plain text (false)

    $mail->Subject = "This is a Sampleenter code here Email";
    $mail->Body    = $message;
    $mail->AltBody = "This is the body in plain text for non-HTML mail clients";
    $mail->AddEmbeddedImage('images/logo.png', 'logo', 'logo.png');
    $mail->addAttachment('files/file.xlsx');

    if(!$mail->Send())
    {
       echo "Message could not be sent. <p>";
       echo "Mailer Error: " . $mail->ErrorInfo;
       exit;
    }

    echo "Message has been sent";
}

有几种可能性:

您正面临服务器问题。服务器上没有邮件服务器。所以你的邮件不能工作，因为你的代码是好的，邮件是有类型的。 您没有得到发布的值。尝试使用静态值的代码。 使用SMTP邮件发送邮件…

总是尝试在邮件函数中发送标题。 如果您通过localhost发送邮件，则执行SMTP设置以发送邮件。 如果您通过服务器发送邮件，请检查您的服务器上是否启用了电子邮件发送功能。

大多数情况下，在共享主机中禁用了mail()函数。 更好的选择是使用SMTP。最好的选择是Gmail或SendGrid。

SMTPconfig.php

<?php 
    $SmtpServer="smtp.*.*";
    $SmtpPort="2525"; //default
    $SmtpUser="***";
    $SmtpPass="***";
?>

SMTPmail.php

<?php
class SMTPClient
{

    function SMTPClient ($SmtpServer, $SmtpPort, $SmtpUser, $SmtpPass, $from, $to, $subject, $body)
    {

        $this->SmtpServer = $SmtpServer;
        $this->SmtpUser = base64_encode ($SmtpUser);
        $this->SmtpPass = base64_encode ($SmtpPass);
        $this->from = $from;
        $this->to = $to;
        $this->subject = $subject;
        $this->body = $body;

        if ($SmtpPort == "") 
        {
            $this->PortSMTP = 25;
        }
        else
        {
            $this->PortSMTP = $SmtpPort;
        }
    }

    function SendMail ()
    {
        $newLine = "\r\n";
        $headers = "MIME-Version: 1.0" . $newLine;  
        $headers .= "Content-type: text/html; charset=iso-8859-1" . $newLine;  

        if ($SMTPIN = fsockopen ($this->SmtpServer, $this->PortSMTP)) 
        {
            fputs ($SMTPIN, "EHLO ".$HTTP_HOST."\r\n"); 
            $talk["hello"] = fgets ( $SMTPIN, 1024 ); 
            fputs($SMTPIN, "auth login\r\n");
            $talk["res"]=fgets($SMTPIN,1024);
            fputs($SMTPIN, $this->SmtpUser."\r\n");
            $talk["user"]=fgets($SMTPIN,1024);
            fputs($SMTPIN, $this->SmtpPass."\r\n");
            $talk["pass"]=fgets($SMTPIN,256);
            fputs ($SMTPIN, "MAIL FROM: <".$this->from.">\r\n"); 
            $talk["From"] = fgets ( $SMTPIN, 1024 ); 
            fputs ($SMTPIN, "RCPT TO: <".$this->to.">\r\n"); 
            $talk["To"] = fgets ($SMTPIN, 1024); 
            fputs($SMTPIN, "DATA\r\n");
            $talk["data"]=fgets( $SMTPIN,1024 );
            fputs($SMTPIN, "To: <".$this->to.">\r\nFrom: <".$this->from.">\r\n".$headers."\n\nSubject:".$this->subject."\r\n\r\n\r\n".$this->body."\r\n.\r\n");
            $talk["send"]=fgets($SMTPIN,256);
            //CLOSE CONNECTION AND EXIT ... 
            fputs ($SMTPIN, "QUIT\r\n"); 
            fclose($SMTPIN); 
            // 
        } 
        return $talk;
    } 
}
?>

contact_email.php

<?php 
include('SMTPconfig.php');
include('SMTPmail.php');
if($_SERVER["REQUEST_METHOD"] == "POST")
{
    $to = "";
    $from = $_POST['email'];
    $subject = "Enquiry";
    $body = $_POST['name'].'</br>'.$_POST['companyName'].'</br>'.$_POST['tel'].'</br>'.'<hr />'.$_POST['message'];
    $SMTPMail = new SMTPClient ($SmtpServer, $SmtpPort, $SmtpUser, $SmtpPass, $from, $to, $subject, $body);
    $SMTPChat = $SMTPMail->SendMail();
}
?>