SMTP Error: Could not connect to SMTP host. Connection failed. stream_socket_enable_crypto(): SSL operation failed with code 1. OpenSSL Error

PHPMailer 要透過 AWS SES 發信時，出現錯誤訊息：

SMTP Error: Could not connect to SMTP host. 
Connection failed. stream_socket_enable_crypto(): SSL operation failed with code 1. 
OpenSSL Error messages:error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed

快速解法：

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

1.
下載 https://curl.haxx.se/ca/cacert.pem

放到 /etc/ssl

(相關資訊: CA certificates extracted from Mozilla )

2.
/etc/php.ini 新增兩行設定：

openssl.cafile = /etc/ssl/cacert.pem
curl.cainfo = /etc/ssl/cacert.pem

重啟 php-fpm 即可

SES 範例程式

<?php

date_default_timezone_set("Asia/Taipei");

#維吉尼亞Virginia
$ses_server    = "email-smtp.us-east-1.amazonaws.com";
$ses_port      = 587;              
$ses_username  = "AKIAYYIC6RQ....";
$ses_password  = "BKJOjEBC5SvBWyQPAX....";

$FROM="[email protected]";
$FROM_NAME="myname";

$MAILTO ='[email protected]';

$MSUBJECT  = "EMAIL SUBJECT";
$MAILBODY = "EMAIL TEST";

#----------------------------------------------------------------
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

require 'PHPMailer/src/Exception.php';
require 'PHPMailer/src/PHPMailer.php';
require 'PHPMailer/src/SMTP.php';

$phpmail    = new PHPMailer();

$phpmail->SMTPAuth   = true;
$phpmail->SMTPSecure = "tls";
$phpmail->Host       = $ses_server;
$phpmail->Port       = $ses_port;
$phpmail->Username   = $ses_username;
$phpmail->Password   = $ses_password;

$phpmail->IsSMTP(true);
// 0 = off (for production use)
// 1 = client messages
// 2 = client and server messages
$phpmail->SMTPDebug  = 2;
#$phpmail->IsHTML(true);
$phpmail->SMTPKeepAlive = true;
$phpmail->CharSet    = "utf-8";
$phpmail->Subject    = $MSUBJECT;
$phpmail->MsgHTML($MAILBODY);

$phpmail->SetFrom   ($FROM, $FROM_NAME);
$phpmail->AddReplyTo($FROM, $FROM_NAME);
$phpmail->AddAddress($MAILTO, '');

echo "to: $MAILTO   \n";

if(!$phpmail->Send()) {
    echo "  Mailer Error: " . $phpmail->ErrorInfo;

} else {
    echo "  Message sent!\n\n";

}

$phpmail->ClearAllRecipients();

其它參考：

• how to fix stream_socket_enable_crypto(): SSL operation failed with code 1
• PHPMailer - OpenSSL Error
• PHPMailer
• 使用AWS SDK for PHP版本 3 的亞馬遜 SES 示例