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Fix Roundcube Webmail SMTP Settings

Fix Roundcube webmail SMTP configuration issues. Configure SMTP server settings, authentication, and resolve email sending problems.

Published: Apr 27, 20267 min readBy FixWikiHub Editorial Team

Illustration of email delivery checks and DNS authentication records.

# Fix Roundcube Webmail SMTP Settings

Roundcube webmail can't send emails due to SMTP configuration issues. Users get errors when trying to send messages through the webmail interface.

Introduction

This article covers troubleshooting steps and solutions for Fix Roundcube Webmail SMTP Settings. The error typically occurs in production environments and can cause service disruptions if not addressed promptly.

Symptoms

Common error messages include:

```php <?php // config/config.inc.php

// SMTP configuration $config['smtp_server'] = 'tls://smtp.example.com'; $config['smtp_port'] = 587; $config['smtp_user'] = '%u'; // Use current username $config['smtp_pass'] = '%p'; // Use current password $config['smtp_auth_type'] = 'LOGIN'; $config['smtp_auth_cid'] = null; $config['smtp_auth_pw'] = null; $config['smtp_secure'] = 'tls'; ```

bash

SMTP Error: Could not connect to SMTP host

```php // Check SMTP server address $config['smtp_server'] = 'tls://smtp.example.com'; // Note: tls:// prefix $config['smtp_port'] = 587;

// Or for SSL $config['smtp_server'] = 'ssl://smtp.example.com'; $config['smtp_port'] = 465;

// Or for no encryption (not recommended) $config['smtp_server'] = 'smtp.example.com'; $config['smtp_port'] = 25; ```

Common Causes

Configuration misconfiguration
Missing or incorrect credentials
Network connectivity issues
Version compatibility problems
Resource exhaustion or limits
Permission or access denied

Step-by-Step Fix

1.Check logs for specific error messages
2.Verify configuration settings
3.Test network connectivity
4.Review recent changes
5.Apply corrective action
6.Verify the fix

Understanding Roundcube SMTP Configuration

1.Roundcube uses two methods for SMTP:
2.PHP mail() function - Uses local mail server
3.SMTP server - Connects to external SMTP server

Configuration File

The main configuration is in config/config.inc.php:

```php <?php // config/config.inc.php

Common Issues and Solutions

Issue 1: SMTP Connection Failed

bash

SMTP Error: Could not connect to SMTP host

Solution:

```php // Check SMTP server address $config['smtp_server'] = 'tls://smtp.example.com'; // Note: tls:// prefix $config['smtp_port'] = 587;

// Or for SSL $config['smtp_server'] = 'ssl://smtp.example.com'; $config['smtp_port'] = 465;

// Or for no encryption (not recommended) $config['smtp_server'] = 'smtp.example.com'; $config['smtp_port'] = 25; ```

Test SMTP connectivity:

```bash # Test SMTP connection telnet smtp.example.com 587

# Test with OpenSSL openssl s_client -connect smtp.example.com:587 -starttls smtp openssl s_client -connect smtp.example.com:465 ```

Issue 2: Authentication Failed

bash

SMTP Error: Authentication failed

Solution:

```php // Use user's credentials $config['smtp_user'] = '%u'; // Current username $config['smtp_pass'] = '%p'; // Current password

// Or specify fixed credentials $config['smtp_user'] = 'webmail@example.com'; $config['smtp_pass'] = 'password';

// Set authentication type $config['smtp_auth_type'] = 'LOGIN'; // or 'CRAM-MD5', 'PLAIN', 'XOAUTH2' ```

Issue 3: SSL/TLS Certificate Issues

bash

SMTP Error: Certificate verification failed

Solution:

```php // Disable certificate verification (not recommended for production) $config['smtp_conn_options'] = array( 'ssl' => array( 'verify_peer' => false, 'verify_peer_name' => false, 'allow_self_signed' => true ) );

// Or specify CA certificate $config['smtp_conn_options'] = array( 'ssl' => array( 'cafile' => '/etc/ssl/certs/ca-certificates.crt', 'verify_peer' => true, 'verify_peer_name' => true ) ); ```

Issue 4: SMTP Timeout

bash

SMTP Error: Connection timed out

Solution:

```php // Increase timeout $config['smtp_timeout'] = 60; // seconds

// Check firewall allows SMTP port // Check SMTP server is reachable ```

bash

# Test connectivity
nc -zv smtp.example.com 587

Issue 5: Wrong SMTP Port

```php // Common SMTP ports: // 25 - Standard SMTP (often blocked) // 465 - SMTPS (SSL) // 587 - Submission (TLS)

// For TLS (STARTTLS) $config['smtp_server'] = 'tls://smtp.example.com'; $config['smtp_port'] = 587;

// For SSL (SMTPS) $config['smtp_server'] = 'ssl://smtp.example.com'; $config['smtp_port'] = 465; ```

Issue 6: Local Postfix Configuration

If using local Postfix:

php

// Use local mail server
$config['smtp_server'] = 'localhost';
$config['smtp_port'] = 25;
$config['smtp_user'] = '';
$config['smtp_pass'] = '';

Configure Postfix:

```bash # /etc/postfix/main.cf smtpd_sasl_auth_enable = yes smtpd_sasl_type = dovecot smtpd_sasl_path = private/auth smtpd_recipient_restrictions = permit_sasl_authenticated, reject_unauth_destination

# Restart Postfix systemctl restart postfix ```

Issue 7: From Address Not Allowed

bash

SMTP Error: Sender address rejected

Solution:

```php // Force From address to match user $config['mail_force_default'] = true;

// Or allow user to set From $config['mail_force_default'] = false;

// Set allowed domains $config['allowed_hosts'] = array('example.com', 'mail.example.com'); ```

Complete Configuration Example

```php <?php // config/config.inc.php

// Basic settings $config['db_dsnw'] = 'mysql://roundcube:password@localhost/roundcube'; $config['default_host'] = 'tls://imap.example.com'; $config['default_port'] = 993;

// SMTP settings $config['smtp_server'] = 'tls://smtp.example.com'; $config['smtp_port'] = 587; $config['smtp_user'] = '%u'; $config['smtp_pass'] = '%p'; $config['smtp_auth_type'] = 'LOGIN'; $config['smtp_timeout'] = 60;

// SMTP connection options $config['smtp_conn_options'] = array( 'ssl' => array( 'verify_peer' => true, 'verify_peer_name' => true, 'cafile' => '/etc/ssl/certs/ca-certificates.crt' ) );

// Identity settings $config['identities_level'] = 0; // Allow multiple identities $config['mail_force_default'] = false;

// Logging for debugging $config['smtp_debug'] = true; $config['debug_level'] = 4; $config['smtp_log'] = true; ```

Debugging SMTP Issues

php

// Enable SMTP debug logging
$config['smtp_debug'] = true;
$config['debug_level'] = 4;
$config['smtp_log'] = true;

Check logs:

```bash # Roundcube logs tail -f /var/log/roundcube/errors tail -f /var/log/roundcube/smtp

# Or in Roundcube logs directory tail -f /var/www/roundcube/logs/errors.log ```

Testing SMTP Configuration

```bash # Test SMTP directly swaks --to recipient@example.com \ --from sender@example.com \ --server smtp.example.com \ --port 587 \ --tls \ --auth LOGIN \ --auth-user sender@example.com \ --auth-pass password

# Or with telnet telnet smtp.example.com 587 EHLO localhost STARTTLS AUTH LOGIN # (base64 encoded username and password) MAIL FROM: <sender@example.com> RCPT TO: <recipient@example.com> DATA Subject: Test This is a test. . QUIT ```

Integration with Postfix/Dovecot

```php // For Postfix + Dovecot setup $config['default_host'] = 'localhost'; $config['default_port'] = 143; $config['smtp_server'] = 'localhost'; $config['smtp_port'] = 25;

// Use SASL authentication $config['smtp_user'] = '%u'; $config['smtp_pass'] = '%p'; $config['smtp_auth_type'] = 'PLAIN'; ```

Verification

```bash # Check Roundcube config cat /etc/roundcube/config.inc.php | grep smtp

# Test SMTP connection telnet smtp.example.com 587

# Send test email through Roundcube # Login to webmail and compose message

# Check logs tail -f /var/log/roundcube/errors ```

Prevention

1.[ ] SMTP server address is correct
2.[ ] SMTP port matches encryption method
3.[ ] TLS/SSL prefix in server address
4.[ ] Authentication credentials are correct
5.[ ] Certificate verification configured
6.[ ] Firewall allows SMTP port
7.[ ] SMTP server accepts connections
8.[ ] Enable debug logging for issues
9.[ ] Check Roundcube error logs
10.[ ] Test SMTP with swaks or telnet

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FAQ

Email Troubleshooting FAQs

Common questions about troubleshooting and preventing similar issues

How do I know if this email-issues troubleshooting guide applies to my situation?

This guide is designed for email-issues issues. If you're experiencing similar symptoms described in the article, follow the step-by-step instructions. Start with the most common causes and work through the diagnostic process.

Is it safe to follow these email-issues troubleshooting steps?

Yes, all steps are designed to be safe and non-destructive. We recommend creating backups before making significant changes and testing each step before proceeding to the next.

How long does it typically take to resolve this type of email-issues issue?

Most email-issues issues can be resolved within 30 minutes to 2 hours, depending on the complexity and root cause. Follow the troubleshooting flow to identify and fix the problem efficiently.

How can I prevent this email-issues issue from happening again?

Regular maintenance, monitoring, and following best practices for email-issues configuration can help prevent recurrence. Consider implementing automated checks and alerts for early detection.

Written by

FixWikiHub Editorial Team

Our editorial team consists of experienced DevOps engineers, systems administrators, and cloud architects with hands-on experience in production environments across AWS, Azure, GCP, and on-premises infrastructure.

Every guide undergoes technical review for accuracy and is updated when software versions, commands, or best practices change.

Last updated: Apr 27, 2026

About our team

Important Notice

Disclaimer & Safety Guidelines

The troubleshooting steps in this guide are provided for educational and informational purposes. Before applying any changes to production systems:

Test in a staging environment first — Always verify commands and configurations in a non-production environment before deploying to live systems.
Create backups — Ensure you have current backups of databases, configurations, and critical files before making changes.
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Resources

Official Documentation & Further Reading

For authoritative information, consult the official documentation for the technologies discussed in this guide. Our troubleshooting content supplements, but does not replace, vendor documentation.

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Fix Roundcube Webmail SMTP Settings

Introduction

Symptoms

Common Causes

Step-by-Step Fix

Understanding Roundcube SMTP Configuration

Configuration File

Common Issues and Solutions

Issue 1: SMTP Connection Failed

Issue 2: Authentication Failed

Issue 3: SSL/TLS Certificate Issues

Issue 4: SMTP Timeout

Issue 5: Wrong SMTP Port

Issue 6: Local Postfix Configuration

Issue 7: From Address Not Allowed

Complete Configuration Example

Debugging SMTP Issues

Testing SMTP Configuration

Integration with Postfix/Dovecot

Verification

Prevention

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People also search for

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FixWikiHub Editorial Team

Disclaimer & Safety Guidelines

Official Documentation & Further Reading