PHPMailer: SMTP Error: Could not connect to SMTP host

问题

I\'ve used PHPMailer on several projects but now I\'m stuck. It gives me the error:
SMTP Error: Could not connect to SMTP host.
I\'ve tried sending email from Thunderbird and it works ! But not through PHPMailer ... Here are the settings from Thunderbird:

Server name: mail.exampleserver.com
Port: 587
Username: user@exampleserver.com
Secure Authentication: No
Connection Security: STARTTLS

I\'ve compared these with the server at my last project where I used PHPMailer and they were:

Server name: mail.exampleserver2.com
Port: 465
Username: user@exampleserver2.com
Secure Authentication: No
Connection Security: SSL/TLS

My php code is:

 $mail = new PHPMailer();
 $mail->IsSMTP(); // send via SMTP
 $mail->Host = SMTP_HOST; // SMTP servers
 $mail->Port = SMTP_PORT; // SMTP servers
 $mail->SMTPAuth = true; // turn on SMTP authentication
 $mail->Username = SMTP_USER; // SMTP username
 $mail->Password = SMTP_PASSWORD; // SMTP password
 $mail->From = MAIL_SYSTEM;
 $mail->FromName = MAIL_SYSTEM_NAME;
 $mail->AddAddress($aSecuredGetRequest[\'email\']);
 $mail->IsHTML(true); // send as HTML

Where I am wrong?

回答1:

Since this questions shows up high in google, I'd like to share here my solution for the case where PHP was just upgraded to version 5.6 (which has stricter SSL behavior).

The PHPMailer wiki has a section on this:

https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting#php-56-certificate-verification-failure

The suggested workaround is including the following piece of code:

$mail->SMTPOptions = array(
    'ssl' => array(
        'verify_peer' => false,
        'verify_peer_name' => false,
        'allow_self_signed' => true
    )
);

This should work for PHPMailer 5.2.10 (and up).

Note: Obviously, and also as suggested in that wiki, this should be a temporary solution!

The correct fix for this is to replace the invalid, misconfigured or self-signed certificate with a good one.

回答2:

In my case it was a lack of SSL support in PHP which gave this error.

So I enabled extension=php_openssl.dll

$mail->SMTPDebug = 1; also hinted towards this solution.

Update 2017

$mail->SMTPDebug = 2;, see: https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting#enabling-debug-output

回答3:

Your problem is most likely this

Connection Security: STARTTLS Connection Security: SSL/TLS

Those are 2 different protocols, are you using the correct one, whatever one you're using in Thunderbird needs to be used.

Try setting the variable:

// if you're using SSL
$mail->SMTPSecure = 'ssl';
// OR use TLS
$mail->SMTPSecure = 'tls';

回答4:

I had a similar issue and figured out that it was the openssl.cafile configuration directive in php.ini that needed to be set to allow verification of secure peers. You just set it to the location of a certificate authority file like the one you can get at http://curl.haxx.se/docs/caextract.html.

This directive is new as of PHP 5.6 so this caught me off guard when upgrading from PHP 5.5.

回答5:

I had the same problem and it was because PHPMailer realized the server supported STARTTLS so it tried to automatically upgrade the connection to an encrypted connection. My mail server is on the same subnet as the web server within my network which is all behind our domain firewalls so I'm not too worried about using encryption (plus the generated emails don't contain sensitive data anyway).

So what I went ahead and did was change the SMTPAutoTLS to false in the class.phpmailer.php file.

/**
 * Whether to enable TLS encryption automatically if a server supports it,
 * even if `SMTPSecure` is not set to 'tls'.
 * Be aware that in PHP >= 5.6 this requires that the server's certificates are valid.
 * @var boolean
 */
public $SMTPAutoTLS = false;

回答6:

does mail.exampleserver.com exist ??? , if not try the following code (you must have gmail account)

$mail->SMTPSecure = "ssl";  
$mail->Host='smtp.gmail.com';  
$mail->Port='465';   
$mail->Username   = 'you@gmail.com'; // SMTP account username
$mail->Password   = 'your gmail password';  
$mail->SMTPKeepAlive = true;  
$mail->Mailer = "smtp"; 
$mail->IsSMTP(); // telling the class to use SMTP  
$mail->SMTPAuth   = true;                  // enable SMTP authentication  
$mail->CharSet = 'utf-8';  
$mail->SMTPDebug  = 0;

回答7:

Followed code worked for me:

$mail = new PHPMailer(true);

$mail->isSMTP();// Set mailer to use SMTP
$mail->CharSet = "utf-8";// set charset to utf8
$mail->SMTPAuth = true;// Enable SMTP authentication
$mail->SMTPSecure = 'tls';// Enable TLS encryption, `ssl` also accepted

$mail->Host = 'smtp.gmail.com';// Specify main and backup SMTP servers
$mail->Port = 587;// TCP port to connect to
$mail->SMTPOptions = array(
    'ssl' => array(
        'verify_peer' => false,
        'verify_peer_name' => false,
        'allow_self_signed' => true
    )
);
$mail->isHTML(true);// Set email format to HTML

$mail->Username = 'Sender Email';// SMTP username
$mail->Password = 'Sender Email Password';// SMTP password

$mail->setFrom('example@mail.com', 'John Smith');//Your application NAME and EMAIL
$mail->Subject = 'Test';//Message subject
$mail->MsgHTML('HTML code');// Message body
$mail->addAddress('User Email', 'User Name');// Target email


$mail->send();

回答8:

$mail->SMTPDebug = 2; // to see exactly what's the issue

In my case this helped:

$mail->SMTPSecure = false;
$mail->SMTPAutoTLS = false;

回答9:

I had a similar issue. I had installed PHPMailer version 1.72 which is not prepared to manage SSL connections. Upgrading to last version solved the problem.

回答10:

Since this is a popular error, check out the PHPMailer Wiki on troubleshooting.

Also this worked for me

$mailer->Port = '587';

回答11:

In my case in CPANEL i have 'Register mail ids' option where i add my email address and after 30 minutes it works fine with simple php mail function.

来源：https://stackoverflow.com/questions/3477766/phpmailer-smtp-error-could-not-connect-to-smtp-host

标签

php

phpmailer