Laravel Gmail SMTP Issues on cPanel: Timeout & SSL Errors (Works Locally)

I’m trying to send emails using Laravel’s Mail facade with Gmail SMTP on a cPanel server. While the configuration works perfectly on my local environment, on the server I’m encountering two different issues:

  1. Timeout errors when trying to connect to Gmail’s SMTP server
  2. SSL certificate verification failures

These issues persist despite successful SSL and port tests. I’ve confirmed that basic connectivity works:

  • Port tests succeed (connection establishes in 71ms)
  • OpenSSL tests show successful TLS negotiation
  • Server can reach Gmail SMTP servers

I’ve tried multiple configuration approaches including:

  • Using both SSL (465) and TLS (587) ports
  • Different encryption methods (SSL/TLS)
  • Various SSL verification settings
  • Different SMTP hosts (smtp.gmail.com and smtp-relay.gmail.com)
  • Adjusting timeout values
  • Different authentication modes

Each attempt results in either a timeout or an SSL certificate verification error, even though the same configuration works flawlessly in the local environment.

Environment:

  • Laravel version 11.34.2
  • PHP 8.2.25
  • cPanel server
  • Gmail SMTP

Configuration Working on Local:

'smtp' => [
            'transport' => 'smtp',
            'url' => null,
            'host' => 'smtp.gmail.com',
            'port' => 587,
            'encryption' => 'tsl',
            'username' => '[email protected]',
            'password' => "app-password",
            'timeout' => null,
        ],

Error #1 – Timeout:

Error sending: SMTP Error: Could not connect to SMTP host.

Configuration USED:

'smtp' => [
    'transport' => 'smtp',
    'host' => 'smtp.gmail.com',
    'port' => 465,
    'encryption' => 'ssl',
    'username' => '[email protected]',
    'password' => 'app-password',
    'timeout' => 5,
    'stream_options' => [
        'ssl' => [
            'verify_peer' => false,
            'verify_peer_name' => false,
            'allow_self_signed' => true,
        ]
    ]
],

Error #2 – SSL Certificate:

Error sending: SMTP Error: Could not connect to SMTP host. 
Connection failed. stream_socket_enable_crypto(): SSL operation failed with code 1. 
OpenSSL Error messages: error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed

Configuration USED:

'smtp' => [
    'transport' => 'smtp',
    'host' => 'smtp-relay.gmail.com',
    'port' => 587,              
    'encryption' => 'tls',          
    'username' => env('MAIL_USERNAME'),
    'password' => env('MAIL_PASSWORD'),
    'timeout' => 5,
    'auth_mode' => 'PLAIN',
    'stream_options' => [
        'tcp' => [
            'tcp_nodelay' => true,
        ],
        'ssl' => [
            'verify_peer' => false,
            'verify_peer_name' => false,
            'allow_self_signed' => true,
            'SNI_enabled' => true,
        ]
    ]
],
  1. Port tests show successful connections:
$ time nc -zv -w 5 smtp.gmail.com 465
Connection to smtp.gmail.com 465 port [tcp/submissions] succeeded!
real    0m0.071s
  1. OpenSSL test shows successful TLS negotiation:
$ openssl s_client -connect smtp.gmail.com:465
...
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
...
220-smtp.gmail.com ESMTP ready
  1. Verified Exim settings:
$ sudo exim -bP accept_8bitmime
accept_8bitmime
$ sudo exim -bP smtp_accept_max_nonmail
smtp_accept_max_nonmail = 10
  1. Tried both SSL (465) and TLS (587) ports
  2. Tried different timeout values
  3. Verified Gmail app password and 2FA settings
  4. Added various SSL/TLS configurations and certificate verifications
  5. Tried using smtp-relay.gmail.com

The connection tests succeed but Laravel’s mailer consistently times out. The quick netcat connection (71ms) suggests the issue might be during SSL handshake or SMTP authentication, but I haven’t been able to resolve it.

Any help would be appreciated.