NimblyMail SMTP

NimblyMail is a comprehensive SMTP and email logging plugin designed to fix WordPress email deliverability issues. By default, WordPress uses the unreliable PHP mail() function, which often causes emails to land in the spam folder or never deliver. NimblyMail solves this by reconfiguring WordPress to securely route your site's emails through a proper SMTP server or dedicated email provider. Whether you need to connect via a standard SMTP host, Gmail OAuth, Microsoft 365 OAuth, Amazon SES, Resend, SendLayer, Brevo, or ZeptoMail, NimblyMail ensures your emails reach the inbox. Plus, with comprehensive email logging, a background queue, a developer sandbox, and an automated deliverability audit, you get full delivery monitoring and one-click troubleshooting. At a glance

• Nine email providers — SMTP, Gmail OAuth, Outlook / Microsoft 365 OAuth, Amazon SES, Resend, SendLayer, Brevo, ZeptoMail, and PHP mail.
• Free Email Logging — Comprehensive log with search, status filters, and one-click resend of failed emails.
• Background Queue — Defer wp_mail() calls to a non-blocking queue powered by Action Scheduler, with three-tier priority, exponential backoff retries, and admin tools to retry or cancel pending mail.
• Developer Sandbox — Stop staging and local environments from sending real email. Choose Log Only (capture and short-circuit) or Redirect (rewrite every recipient to a single safe address). Optional allowlist for addresses that should bypass the sandbox.
• Deliverability Health Audit — Automated DNS-based audit of SPF, DKIM, DMARC, and PTR for the active sender domain, with scheduled checks and human-readable findings per pillar.
• Clean, Modern Dashboard — Delivery stats, connection health, queue health widget, deliverability summary, and recent activity at a glance.
• Selectively disable WordPress notification emails across 8 categories (over 25 individual triggers).
• Failure alerts delivered via PHP's native mail() so a broken transport can't silence them.
• AES-256-CBC credential encryption with optional PHP-constant overrides in wp-config.php.
• First-class WordPress Multisite support with network defaults, per-site overrides, and per-field locks.
• Guided setup wizard with auto-detection and one-click import from existing SMTP plugins.

Supported Email Providers

• Other SMTP — Connect to any SMTP server (Outlook, Office 365, Mailgun, SendGrid, Zoho, etc.)
• Gmail / Google Workspace — Authenticate securely via Google OAuth without managing your own Google Cloud credentials.
• Outlook / Microsoft 365 — Authenticate via Microsoft OAuth and send through smtp.office365.com without registering your own Azure application.
• Amazon SES — Send via AWS Simple Email Service
• Resend — Modern email API for developers
• SendLayer — Transactional email delivery service
• Brevo — Transactional email API (formerly Sendinblue)
• ZeptoMail — Zoho's transactional email service with regional endpoints
• Default (PHP) — Fallback to the built-in PHP mail function

Email Logging Every outgoing email is logged with recipient, subject, status, headers, and optional body capture. Search and filter logs by status (sent, failed, pending), resend failed emails with one click, and view full message details in a modal preview. Background Queue Turn the queue on under NimblyMail > Settings > Mail Queue and every wp_mail() call returns immediately. Messages are persisted to a database queue, dispatched by Action Scheduler in priority order (high / normal / bulk), and retried with exponential backoff on transient failures. Attachments are staged on enqueue so request-scoped tmp files cannot break delayed delivery. The Queue admin screen lists pending and failed items with retry / cancel actions, and the dashboard surfaces a queue-health widget. Test emails and admin alerts continue to send synchronously by default so you always get immediate feedback. Developer Sandbox Working on a staging copy or local clone? Turn on the sandbox to guarantee no real customer ever receives an accidental email. Pick Log Only to capture and short-circuit every wp_mail() call so they show up in the Email Log without leaving the host, or Redirect to rewrite every recipient to a single safe address with the originals preserved in X-NimblyMail-Original-* headers and a configurable subject prefix. An allowlist (exact email or *@domain.com) lets through addresses you do want delivered for testing. Sandboxing is settings-driven, switchable from the Network Admin on multisite, and visible at a glance via an admin-bar badge. Deliverability Health Audit NimblyMail runs an automated DNS audit of the active sender domain on a schedule (and on demand) and surfaces the result on the Deliverability page and the dashboard. The audit covers four pillars — SPF, DKIM, DMARC, and PTR — and is mailer-aware: required SPF includes and DKIM selectors are sourced from whichever provider you have configured (Gmail, Outlook 365, SES, etc.), with skip explanations for cases where a check does not apply. Findings are human-readable: each pillar shows pass/warn/fail with a one-line reason and a link to the relevant provider documentation. Email Controls Selectively disable WordPress notification emails you don't need — comment notifications, password reset emails, new user registrations, automatic update notices, and more. Over 25 individual email types across 8 categories can be toggled on or off. Failure Alerts Receive instant alerts when emails fail to deliver. Configure alert recipients with optional CC and BCC addresses. Alerts are sent via PHP's native mail function to bypass the broken transport. Security Credentials (SMTP passwords, API keys) are encrypted at rest using AES-256-CBC with HMAC-SHA256 verification. Settings can be locked via PHP constants in wp-config.php, making sensitive fields read-only in the admin UI. Settings Import Migrating from another SMTP plugin? NimblyMail automatically detects existing SMTP-plugin configurations and offers one-click import through the setup wizard. WordPress Multisite First-class multisite support. Network-activate the plugin once and every sub-site inherits the network defaults until a site admin explicitly overrides a field. Super admins get a Network Admin → NimblyMail surface with an aggregated dashboard, a sites table, per-field locks, and a per-site override editor. Clean Dashboard Built with Vue 3 and Ant Design, the dashboard is fast, responsive, and designed to feel native to WordPress. A guided setup wizard helps you configure everything in minutes, while the main dashboard provides a clear overview of your email delivery health.

1.0.1

• Maintenance release with compatibility tested up to WordPress 7.0.

1.0.0

• Initial release.
• Nine email providers: PHP mail, SMTP, Gmail OAuth, Outlook / Microsoft 365 OAuth, Amazon SES, Resend, SendLayer, Brevo, ZeptoMail.
• Comprehensive email logging with search, filters, and resend.
• Background queue with three-tier priority, exponential backoff retries, attachment staging, and admin retry/cancel tools.
• Developer Sandbox with Log Only and Redirect modes plus an allowlist for bypass addresses.
• Automated deliverability health audit covering SPF / DKIM / DMARC / PTR with mailer-aware requirements.
• Email controls to toggle 25+ WordPress notification emails.
• Failure alerts with CC/BCC support.
• AES-256-CBC credential encryption with HMAC-SHA256 verification.
• Per-install signed-refresh OAuth proxy protocol — leaked refresh tokens cannot be replayed against the proxy from arbitrary hosts.
• PHP constants support for wp-config.php overrides.
• Settings import from supported existing SMTP plugins.
• Guided setup wizard with auto-detection.
• Modern Vue 3 admin interface.