How to Configure SMTP Settings in WordPress

What Is SMTP?

SMTP (Simple Mail Transfer Protocol) is the industry standard for sending email. WordPress’s default email function (mail()) uses the server’s local mail transfer agent (MTA), which is often misconfigured, blocked by ISPs, or flagged as spam. SMTP uses authenticated connections to a dedicated email service (Gmail, Outlook, SendGrid, etc.), which dramatically improves deliverability.

The Classic Monks SMTP Settings feature adds a configuration interface for SMTP. Once enabled, every email WordPress sends goes through your configured SMTP server instead of the default mail().

Why You Need It

The default WordPress email function has several problems:

• Spam folder placement: Most modern email providers (Gmail, Outlook, etc.) flag emails from mail() as spam because the sending server isn’t authenticated
• No authentication: Without SPF, DKIM, and DMARC records, the emails look suspicious
• Server limitations: Many shared hosts block outbound SMTP on port 25; mail() falls back to local delivery which often fails
• No retry logic: If an email fails, it’s lost
• No analytics: You can’t see delivery rates, open rates, or bounce rates

Using SMTP through a dedicated email service fixes all of these. Services like SendGrid, Mailgun, and Postmark have dedicated infrastructure for transactional email with high deliverability, authentication, and analytics.

How to Configure SMTP Settings in Classic Monks

Step 1: Navigate to Settings

Click into the Classic Monks plugin settings in your WordPress dashboard.

Step 2: Go to the Email Tab

Click on the Email menu. The Email Settings subtab opens by default.

Step 3: Enable SMTP Settings

Toggle on Enable SMTP Settings. A notice appears indicating that the Email submenu will be added and a page reload is required.

Step 4: Save Changes

Click Save Changes.

Step 5: Reload the Admin

Reload the WordPress admin page. The Email submenu now appears under Classic Monks.

Step 6: Navigate to the SMTP Submenu

Click Classic Monks > Email. The SMTP configuration form appears.

Step 7: Choose a Provider Preset (or Custom)

Select your email provider from the Provider dropdown:

• Gmail / Google Workspace: For Gmail or Google Workspace accounts
• Outlook / Office 365: For Microsoft email
• SendGrid: For SendGrid transactional email
• Mailgun: For Mailgun transactional email
• Amazon SES: For AWS Simple Email Service
• Postmark: For Postmark transactional email
• Custom SMTP: For any other SMTP server

Each preset auto-fills the host, port, and encryption settings. You only need to enter the credentials.

Step 8: Enter SMTP Credentials

For most providers, you need:

• Username: Your email address or API key
• Password: Your email password or API key (for some providers, you need an “app password” instead of the account password)
• From Email: The email address that will appear as the sender (must be verified with your provider)
• From Name: The display name that will appear as the sender

Step 9: (Optional) Configure Advanced Settings

Most users can skip this. Advanced options include:

• Encryption: SSL/TLS (recommended), STARTTLS, or None (insecure)
• Port: SMTP port (usually 587 for TLS, 465 for SSL, 25 for unencrypted)
• Authentication: Whether to require authentication (almost always yes)

Step 10: Save Changes

Click Save Changes.

Step 11: Send a Test Email

From the SMTP configuration page, enter an email address and click Send Test Email. The plugin attempts to send a test message via your configured SMTP server. If the test succeeds, your SMTP is working. If it fails, the error message tells you what went wrong.

Configuration Options

Option	Description	Default
Enable SMTP Settings	Master toggle.	Off
Provider	Predefined provider preset or “Custom SMTP”.	Custom SMTP
SMTP Host	The SMTP server hostname (e.g., smtp.gmail.com).	Empty
SMTP Port	The SMTP port (587 for TLS, 465 for SSL).	587
Encryption	SSL/TLS, STARTTLS, or None.	TLS
Username	SMTP authentication username.	Empty
Password	SMTP authentication password (or app password).	Empty
From Email	The sender email address.	Empty
From Name	The sender display name.	Empty

Common Provider Configurations

Provider	Host	Port	Encryption	Notes
Gmail / Google Workspace	smtp.gmail.com	587	TLS	Requires an “App Password” (not your account password). Enable 2FA on the Google account, then create an App Password in Google Account settings.
Outlook / Office 365	smtp.office365.com	587	STARTTLS	Standard account credentials work. For MFA-enabled accounts, an App Password may be required.
SendGrid	smtp.sendgrid.net	587	TLS	Username is literally apikey; password is your SendGrid API key.
Mailgun	smtp.mailgun.org	587	TLS	Standard SMTP credentials from your Mailgun domain.
Amazon SES	email-smtp.<region>.amazonaws.com	587	TLS	Requires SMTP credentials (separate from AWS console credentials). Get them from the SES console under “SMTP Settings”.
Postmark	smtp.postmarkapp.com	587	TLS	Server token as both username and password.

What Gets Affected

When SMTP is enabled, ALL emails WordPress sends are routed through your configured SMTP server:

• Password reset emails
• New user registration emails
• Comment notification emails
• WooCommerce transactional emails
• Contact form emails (Contact Form 7, WPForms, etc.)
• Plugin notification emails
• Any email sent via wp_mail()

The change is global. There is no per-email-type override.

Advanced Options (Developers)

This feature registers 4 WordPress hooks in submenu/smtp-settings.php:

Actions:

• phpmailer_init calls cm_smtp_configure_phpmailer_enhanced() (Configures PHPMailer with SMTP settings)

Filters:

• cron_schedules calls cm_register_email_cron_schedules() (Registers retry queue cron schedule)
• cm_email_max_connection_attempts calls apply_filters() (Customizable filter)
• cm_email_allow_wp_mail_fallback_after_provider_failure calls apply_filters() (Customizable filter)

// Hooked in submenu/smtp-settings.php
add_action( 'phpmailer_init', 'cm_smtp_configure_phpmailer_enhanced' );

The feature modifies WordPress behavior by registering or removing hooks. Disabling it reverses those changes.

Troubleshooting

The test email fails with “SMTP connect() failed”

Cause: The SMTP host, port, or encryption is wrong, or the SMTP server is unreachable from your hosting.
Fix: Verify the host, port, and encryption against the provider’s documentation. Test connectivity: telnet smtp.gmail.com 587 from the server shell. If telnet fails, your hosting blocks outbound SMTP and you need to ask them to open the port or use a different port.

The test email fails with “Authentication failed”

Cause: Wrong username, wrong password, or the provider requires an App Password instead of the account password.
Fix: For Gmail, create an App Password (Google Account > Security > 2-Step Verification > App passwords). For SendGrid, the username is apikey and the password is the API key. For Amazon SES, generate SMTP credentials separately from your AWS console credentials.

Emails go to spam

Cause: The From Email address is not authenticated with SPF, DKIM, and DMARC records, or the SMTP server has a poor reputation.
Fix: Verify the From Email address is the same as the authenticated account (Gmail won’t let you send as a non-Gmail address without proper DNS setup). Add SPF, DKIM, and DMARC records to your domain. Check the SMTP server’s IP reputation at mxtoolbox.com.

The SMTP submenu doesn’t appear after enabling

Cause: Page reload didn’t trigger the submenu registration.
Fix: Hard-refresh the admin page. If still missing, deactivate and reactivate Classic Monks to trigger full re-registration.

WordPress is still using mail() after enabling SMTP

Cause: Another plugin is overriding the SMTP configuration, or a custom theme function is calling mail() directly instead of wp_mail().
Fix: Check for plugin conflicts by deactivating other SMTP-related plugins (WP Mail SMTP, etc.). Search the theme for mail( calls that bypass wp_mail().

SMTP works for test emails but not for site emails

Cause: The From Email address doesn’t match the authenticated SMTP account. Most SMTP servers refuse to send email from an address they don’t authenticate.
Fix: Set the From Email to the exact address used for SMTP authentication (e.g., [email protected] if authenticated with [email protected]).

Connection times out on shared hosting

Cause: The hosting provider blocks outbound SMTP connections on port 25, 465, or 587.
Fix: Try port 2525 (an alternative SMTP port many providers support). If that doesn’t work, use an HTTP-based email API (SendGrid, Mailgun) via a custom integration rather than SMTP.