SwiftMailer PHP library fails when sending emails through Gmail SMTP

[Noah_Fire]

I’m creating a basic PHP application that sends emails using a Gmail account through SwiftMailer. The script is supposed to send a test message from Gmail to the same Gmail address.

The Problem

My code works fine until it reaches the send method. When I call $emailSender->send($emailMessage), the script stops working completely and nothing after that line gets executed.

Here’s my current code:

<?php
require_once 'vendor/autoload.php';

// Configure SMTP transport for Gmail
$smtpConfig = Swift_SmtpTransport::newInstance('smtp.gmail.com', 587)
    ->setUsername('[email protected]')
    ->setPassword('mypassword123')
;

echo 'Transport configured<br>';

// Create mailer instance
$emailSender = Swift_Mailer::newInstance($smtpConfig);

// Build the email message
$emailMessage = Swift_Message::newInstance('Test Email Subject')
    ->setFrom(array('[email protected]' => 'Test Sender'))
    ->setTo(array('[email protected]' => 'Recipient Name'))
    ->setBody('This is a test email message')
;

echo 'Message created<br>';

// This line causes the script to crash
$sendResult = $emailSender->send($emailMessage);
echo 'Email sent: ' . $sendResult;

?>

Why does the send method cause my script to fail? Is there something wrong with my Gmail SMTP configuration or is this a common SwiftMailer issue?

[MiaDragon42]

check your php error logs - that’s where you’ll find what’s actually breaking your script. gmail’s smtp is probably timing out or rejecting your connection. try adding ->setTimeout(30) to your transport so it won’t hang forever waiting for gmail to respond.

[Emma_Fluffy]

The script freezes at send because of connection timeouts or auth failures that SwiftMailer doesn’t handle well. I’ve seen this exact thing when migrating old email systems. You’re probably missing encryption settings in your SMTP transport config. Add ->setEncryption('tls') to your transport setup. Also, wrap the send call in try-catch to catch any exceptions SwiftMailer’s throwing silently. Gmail SMTP is really picky about connection parameters, and without proper error handling, you won’t see what’s actually breaking. I added error output and timeout settings to debug similar issues where scripts just hung forever.

[livbrown]

The Problem:

Your PHP script using SwiftMailer to send emails from your Gmail account stops execution after calling $emailSender->send($emailMessage). No error messages are displayed, and nothing after that line executes. This suggests an issue with email authentication or a connection problem that SwiftMailer isn’t handling gracefully.

Understanding the “Why” (The Root Cause):

Gmail’s security measures require you to use App Passwords instead of your regular Gmail password when accessing your account through third-party applications like SwiftMailer. When you use your standard password, Gmail blocks the connection for security reasons, resulting in the script silently halting without providing any error messages. SwiftMailer, by default, doesn’t provide robust error handling, leading to this unexpected behavior.

Step-by-Step Guide:

1. Generate a Gmail App Password:

   • Go to your Google Account security settings: https://myaccount.google.com/security
   • If you haven’t already, enable Two-Factor Authentication (2FA).
   • Scroll down to “App Passwords” and click on it.
   • Select “Select app” and choose “Mail.”
   • Select “Select device” and choose “Other (Custom name).” Give it a name like “SwiftMailer.”
   • Click “Generate.” Google will display a 16-character App Password. Copy this password immediately; you won’t be able to see it again.

2. Replace Your Gmail Password with the App Password:

   • Open your PHP script and locate the line where you set the password for your SwiftMailer configuration:

   $smtpConfig = Swift_SmtpTransport::newInstance('smtp.gmail.com', 587)
       ->setUsername('[email protected]')
       ->setPassword('mypassword123') // This line needs to be changed
   ;
   

   • Replace 'mypassword123' with the App Password you generated in Step 1. Do not use your standard Gmail password here.

3. Enable Encryption (Optional but Recommended):

   • Add encryption to your SwiftMailer configuration for a more secure connection. Add this line:

   ->setEncryption('tls')
   

   Your complete $smtpConfig should now look like this:

   $smtpConfig = Swift_SmtpTransport::newInstance('smtp.gmail.com', 587)
       ->setUsername('[email protected]')
       ->setPassword('YOUR_APP_PASSWORD')
       ->setEncryption('tls')
   ;
   

4. Improve Error Handling (Optional but Highly Recommended):

   • Wrap your send call in a try-catch block to handle any exceptions SwiftMailer might throw. This will provide more informative error messages if anything else goes wrong.

   try {
       $sendResult = $emailSender->send($emailMessage);
       echo 'Email sent: ' . $sendResult;
   } catch (Swift_TransportException $e) {
       echo "Error sending email: " . $e->getMessage();
   } catch (Exception $e) {
       echo "An unexpected error occurred: " . $e->getMessage();
   }
   

5. Test Your Script: Run your script again. The improved error handling should provide a specific error message if there are further problems.

Common Pitfalls & What to Check Next:

• Incorrect App Password: Double-check that you copied and pasted the App Password correctly. Generate a new one if you suspect a typo.
• Firewall Issues: Ensure your server’s firewall allows outbound connections on port 587.
• Rate Limits: Gmail might temporarily block your IP address if you send too many emails in a short period. Implement delays between emails if necessary.
• SwiftMailer Version: Make sure you’re using an up-to-date version of SwiftMailer.

Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!

[quirky_quokka23]

Yeah, this Gmail SMTP issue is everywhere. You’ve got the usual auth problems, but you’re also hitting rate limits, timeouts, or Gmail’s security blocks that just freeze your script.

I dealt with this same nightmare building email notifications for deployments. Wasted tons of time on SMTP configs and Gmail’s annoying quirks.

What fixed it? I dropped SMTP completely. Switched to Latenode and built a workflow that handles emails through their platform. No more config hell, no auth issues, and it does retries and error logging automatically.

My setup sends email data from PHP via HTTP request to Latenode, then their service processes and sends it. Way more reliable than wrestling with Gmail SMTP.

You also get real error handling instead of scripts dying silently like yours is doing. You’ll actually see what breaks.

Check it out: https://latenode.com