Why Can\'t My PHPMailer Connect to the SMTP Host?

How to Resolve PHPMailer's "SMTP Error: Could not connect to SMTP host"

PHPMailer, a widely used PHP library for sending emails, occasionally encounters the error message "SMTP Error: Could not connect to SMTP host." This error typically occurs when PHPMailer is unable to establish a connection with the SMTP server specified in the host and port settings.

To troubleshoot this issue, it's crucial to compare the SMTP settings used by PHPMailer to those utilized by a known-working email client like Thunderbird. In this case, the settings from Thunderbird are:

• Server name: mail.exampleserver.com
• Port: 587
• Username: [email protected]
• Secure Authentication: No
• Connection Security: STARTTLS

Next, ensure that the PHP code is correctly configured for the SMTP settings. The provided code sample appears correct, but make sure to verify the following:

• Host: Set this to "mail.exampleserver.com" or the SMTP server address provided by your email provider.
• Port: Set this to 587.
• SMTPAuth: Set this to true to enable SMTP authentication.
• Username: Set this to your email address (e.g., [email protected]).
• Password: Set this to the password associated with your email address.

If the SMTP settings are correct and the issue persists, consider the following solution:

Updating PHP Version for SSL Certification

If you recently upgraded PHP to version 5.6, stricter SSL behavior may have been implemented. PHPMailer's documentation suggests a workaround:

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

Note: This solution is only a temporary fix and should be replaced by a proper fix such as replacing invalid or self-signed certificates with valid ones.

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