Custom SMTP: Email Deliverability – FREE & Easy-to-use for WordPress Plugin Directory

Add Mail SMTP settings for WordPress Looking to modify the SMTP on your WordPress site?

Our Custom SMTP solution offers you this possibility, allowing you to easily change your WordPress SMTP settings, ensuring your emails consistently land in the recipient’s inbox.

Custom SMTP solves your email deliverability problems by reconfiguring WordPress to use a proper SMTP provider when sending emails.

What’s more, our intuitive settings page and comprehensive documentation will guide you through the process, making the task of modifying your SMTP settings easier than ever.

Custom SMTP is a free tool, packed with all the essential features you need to send your WordPress emails with absolute confidence!

Built for modern WordPress: WordPress 7.0 ready, PHPMailer 7.0.2 compatible, stateless / cloud-ready (Docker, Kubernetes), and fully translated in English and French.

Amazon SES API — keyless sending with IAM roles Running WordPress on AWS (ECS Fargate, EC2, App Runner)? Custom SMTP can send through the Amazon SES API authenticated entirely by your container or instance IAM role — with no access keys, no secret keys, and no SMTP credentials stored anywhere. The plugin relies on the AWS default credential chain (the ECS task role / EC2 instance role), so your secrets never live in the database or the settings page.

This is the cleanest, most secure way to send from a containerized, 12-factor WordPress:

Zero stored secrets — authentication comes from the IAM role attached to the task/instance, not from keys pasted into wp-admin.

Full message fidelity — HTML, attachments, CC/BCC, Reply-To and custom headers are preserved (the message is sent as raw MIME); BCC recipients stay hidden.

SES Configuration Sets — optional, for bounce/complaint tracking and CloudWatch metrics.

Environment-driven — region, sender address and configuration set can be injected as environment variables / PHP constants (SES_REGION / AWS_REGION, SES_FROM_EMAIL, SES_CONFIG_SET), so the same image ships across environments without touching the database.

No extra dependency required — works whether or not the AWS SDK for PHP is present; when it isn’t, a built-in, dependency-free signed API client is used.

One-click test — send a test email and get back the SES MessageId.

Config-as-code & Multisite (immutable deployments) For immutable Docker images, DISALLOW_FILE_MODS setups and large networks, every setting can be forced from the environment — no database writes at deploy time:

Any setting via a constant or env variable — define CUSTOM_SMTP_<SETTING> (e.g. CUSTOM_SMTP_MAILER_TYPE=ses_api, CUSTOM_SMTP_HOST, CUSTOM_SMTP_LOG_RETENTION) and it overrides the saved value everywhere. The Amazon SES shortcuts (SES_REGION / AWS_REGION, SES_FROM_EMAIL, SES_CONFIG_SET) keep working too.

Activate a mailer network-wide with one variable — set CUSTOM_SMTP_MAILER_TYPE=ses_api in the container and every site uses Amazon SES, with zero per-site configuration and no custom option_* filter.

Multisite network settings — on a network, settings are read from the network-wide option (get_site_option) beneath any per-site option, so one configuration can apply to the whole network.

Visible in wp-admin — any field supplied by the environment is shown read-only with a “from VARIABLE” badge, so admins see exactly what the platform controls.

Built-in Email Logging Never wonder if your emails were sent again. Custom SMTP automatically logs every email sent from your WordPress site – including WooCommerce order notifications, contact form submissions, and password resets. Preview email content directly in wp-admin, debug delivery issues with detailed error messages, and export logs for compliance.

Configuration Options You can set the following options:

From Name & Email – Specify the sender name and email address for all outgoing emails

SMTP Host – Your email provider’s server (e.g., smtp.gmail.com)

SMTP Port – Common ports: 587 (TLS), 465 (SSL), 25 (None)

Encryption – Choose between None, SSL, or TLS

Authentication – Enable/disable SMTP authentication for relay servers

Username & Password – Your SMTP credentials (password stored encrypted)

Provider Presets – One-click configuration for Gmail, Outlook, iCloud, SendGrid, AWS SES, and more

Amazon SES API (IAM role) – Send through the Amazon SES API with no stored credentials, authenticated by your AWS task/instance role

Key Features SMTP Configuration

* Configure any SMTP server (Gmail, Outlook, SendGrid, Mailgun, AWS SES, etc.)

* Support for SSL/TLS encryption

* Optional SMTP authentication for relay servers

* Test connection without sending emails

* Send test emails to verify configuration

Amazon SES API (keyless, IAM role)

* Send via the Amazon SESv2 API authenticated by your AWS IAM role — no access keys or SMTP credentials stored

* Ideal for AWS ECS/Fargate, EC2 and other containerized, stateless deployments

* Preserves HTML, attachments, CC/BCC, Reply-To and custom headers (raw MIME)

* Optional SES Configuration Set for bounce/complaint/CloudWatch tracking

* Region, sender and configuration set configurable via environment variables or constants

* Works with or without the AWS SDK for PHP (built-in signed API client fallback)

* “Send Test Email” returns the SES MessageId

Email Logging & Debugging

* Zero configuration – Logging works out of the box

* Track all emails sent from WordPress, WooCommerce, Contact Form 7, and any plugin

* View delivery status (sent/failed) with detailed error messages

* Debug wp_mail errors easily – See exactly why emails fail

* Resend failed emails – Re-send a failed message straight from the logs after fixing your configuration

* Store email headers for advanced troubleshooting

* Search by recipient, subject, or status

* Filter by date range (Today, 7 days, 30 days)

* Export logs to CSV for reporting and compliance

Email Preview & Content

* Preview email body directly from wp-admin – No need to send test emails

* View HTML source code of any logged email

* Outlook-style sidebar for quick preview

* Download any email as HTML file for archiving

* Optional content storage (disabled by default for privacy)

Deliverability

* Cooperates with the automatic Envelope-From / Return-Path behavior introduced in WordPress 6.9 — improves SPF, DKIM and DMARC alignment on strict hosts (AWS SES, Postmark, etc.)

* PHPMailer 7.0.2 compatible (the version bundled in WordPress 7.0)

* UTF-8 and emoji handled end-to-end in subjects, bodies, and headers

Privacy & GDPR-friendly

* SMTP password encrypted at rest (AES-256-CBC)

* Configurable log retention with automatic purge (30 days by default)

* Email content storage can be disabled in one click from the settings

* Email preview rendered in a sandboxed iframe — no JavaScript execution from logged emails

* All data stays in your WordPress database — no third-party calls

Security

* SMTP password encrypted in database (AES-256-CBC)

* All admin actions protected with nonces

* Capability checks on all operations

Stateless & Cloud-Ready

* Fully compatible with stateless WordPress hosting (containers, Kubernetes, AWS ECS/Fargate, etc.)

* Works with Bedrock, Trellis, and other modern WordPress stacks

* Zero filesystem writes – all data stored in the database

* No shared storage (EFS/NFS) required between instances

* Safe to run on read-only filesystems

AI & Workflow Integration (WordPress 6.9+)

* custom-smtp/connection-health — read the current SMTP state (configured, host/port/encryption/auth, log retention) from any tool

* custom-smtp/send-test-email — trigger a test email through your configured SMTP server

* Compatible with MCP-enabled AI assistants, automation tools (n8n, Make), dashboards, and other plugins via the WordPress Abilities API

* Protected by capability checks (manage_options) — same security boundary as the wp-admin interface