Why Isn\'t My PHPMailer Connecting to the SMTP Host When Thunderbird Works?

PHPMailer: Troubleshooting SMTP Error: Could Not Connect to SMTP Host

When encountering an SMTP error indicating that the SMTP host could not be connected to, it's essential to verify your PHPMailer configuration and examine the specific settings used in other email applications, such as Thunderbird.

In this case, the user mentioned that PHPMailer was generating the error while sending emails, even though Thunderbird was working successfully with slightly different settings.

PHPMailer Configuration Considerations:

• Ensure that the $mail->Host property matches the server name specified in Thunderbird (e.g., mail.exampleserver.com).
• Verify that the $mail->Port property matches the Thunderbird setting (e.g., 587).
• Check the $mail->Username and $mail->Password properties to confirm they are correct.
• Ensure that $mail->SMTPAuth is set to true to enable SMTP authentication.

Troubleshooting for PHP Version 5.6 and Above:

If the above steps do not resolve the issue, it may be due to stricter SSL behavior introduced in PHP version 5.6. In this case, the following workaround may solve the problem:

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

Important Note:

While this workaround may suppress the error, it should be considered a temporary solution. The ideal solution is to replace the invalid or misconfigured certificate with a valid one.

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