SendForce Mail SMTP Relay – SMTP and vs Simple SMTP

SendForce Mail Relay is a free, open-source WordPress SMTP and email-API plugin that fixes the “WordPress emails not being delivered” problem. Send WooCommerce order emails, Contact Form 7 / WPForms / Gravity Forms submissions, password resets, registration confirmations, and any other wp_mail() traffic through Amazon SES, SendGrid, Mailgun, Brevo (Sendinblue), Postmark, Zoho ZeptoMail, Gmail API, Microsoft 365, or any standard SMTP server — with full email logging, queue, retry, and failure alerts. Why SendForce Mail Relay Free and open-source. Every feature is included — no premium tier, no email-volume cap, no provider paywall. 24+ providers, one plugin. Built-in presets and HTTP API integrations for major transactional email services — pick what fits your budget, deliverability needs, and region. Built-in debugging. Live SMTP debug log on test email, raw API request/response capture in the email log, “Copy Debug Info” button for support tickets, and WP-CLI commands. Designed for developers and agencies who need to diagnose email problems fast. Multiple connections with automatic fallback. Configure a primary connection (e.g. Amazon SES) plus a fallback (e.g. Mailgun). If the primary returns an error, the fallback takes over — no email lost. Supported email providers HTTP API sending (recommended — faster and more reliable than SMTP): Amazon SES (AWS Simple Email Service) SendGrid (by Twilio) Mailgun (by Sinch) Brevo (formerly Sendinblue) SparkPost Postmark Zoho ZeptoMail Microsoft 365 / Outlook (Microsoft Graph API) Gmail / Google Workspace (Gmail API) SMTP2GO SMTP.com Elastic Email SocketLabs Moosend SendLayer Mailjet MailerSend Mandrill (by Mailchimp) Resend Netcore Email API (formerly Pepipost) SMTP sending (works with any provider, including custom servers): Gmail / Google Workspace SMTP (smtp.gmail.com) Microsoft 365 / Outlook SMTP (smtp.office365.com) Yahoo Mail SMTP Zoho Mail SMTP Turbo SMTP Any other SMTP server (host, port, username, password) Features Multiple connections with automatic fallback — configure a primary connection (e.g. Amazon SES) plus a fallback (e.g. Mailgun, SMTP, or PHP mail). If the primary returns an error, the fallback is attempted automatically. Both attempts are logged so you have a full audit trail; recovered emails carry a “Recovered via fallback” badge in the log detail view. Smart Routing Rules — send different emails through different connections based on rules you define. Match by recipient domain, recipient pattern (glob), sender email or domain, source plugin (auto-detected for WooCommerce, Contact Form 7, WPForms, Gravity Forms, Ninja Forms, Fluent Forms, Forminator, Easy Digital Downloads, MemberPress, LearnDash, MailPoet, BuddyPress, bbPress and more), subject contains, time of day, or weekday. Rules are evaluated top-down (first match wins) and can target a single connection, a round-robin pool, or WordPress phpmail(). Includes inline rule editor, master enable/disable toggle, “Test Routing” tool, and a “via rule:” badge on the Email Log so you can see exactly which rule fired for any send. One-click provider presets — pre-filled host, port, encryption, and API endpoint for every supported provider. Just paste your API key or password. Email Log — every outgoing email logged with status, recipient, subject, headers, error message, and timestamp. Filter by status, search by keyword, filter by date range, export to CSV or JSON. Email Queue with retry — queue mode prevents rate-limit errors and timeouts on bulk sends. Failed emails auto-retry on exponential backoff (5 min → 15 min → 45 min). Email Test page — send a test email with live SMTP debug log output. Diagnose connection problems instantly. Failure alerts — push delivery failures to Telegram, Slack, Discord, Microsoft Teams, Google Chat, Pushover, or any custom webhook. Sender Identity override — force every email to use a custom From name and From address site-wide. Conflict detection — warns you if another SMTP plugin (WP Mail SMTP, FluentSMTP, Easy WP SMTP, Post SMTP, etc.) is active so you can deactivate it before things break. Encrypted credential storage — SMTP passwords and API keys are encrypted at rest using AES-256-CBC with a dedicated per-site key, so they survive security-key/salt regeneration. WP-CLI commands — wp sendforce test, wp sendforce queue process, wp sendforce log list, wp sendforce sysinfo. Developer hooks — sendforce_before_send, sendforce_after_send, sendforce_log_entry, sendforce_api_request, sendforce_api_response for extending the plugin without forking. WP_DEBUG_LOG integration — optional mirroring of SMTP and API debug output to debug.log. Automatic log cleanup — configurable retention period (default 30 days). Privacy-friendly — optional disable of email-body logging for GDPR / privacy compliance. Multisite compatible. Works with all major WordPress plugins SendForce Mail Relay hooks into WordPress’s core wp_mail() function, so it works with every plugin that sends email — including WooCommerce, Easy Digital Downloads, Contact Form 7, WPForms, Gravity Forms, Ninja Forms, Fluent Forms, Forminator, MemberPress, LearnDash, BuddyPress, bbPress, MailPoet (transactional), and any custom plugin or theme that uses wp_mail(). External Services SendForce Mail Relay is an email-delivery plugin. It does NOT connect to any external service automatically. A connection is made ONLY after you explicitly configure a provider and either (a) WordPress sends an outgoing email, or (b) you click “Send Test Email”, or (c) you enable a notification channel and an email-failure alert is dispatched. For each configured email provider, the data sent on every send is the same set of fields WordPress would otherwise hand to the local mail() function: the recipient address(es), CC, BCC, Reply-To, From name/address, subject, message body, headers, and attachments. No additional telemetry or analytics is transmitted by this plugin. For each configured notification channel (Telegram, Slack, Discord, Microsoft Teams, Google Chat, Pushover, custom Webhook), the data sent is a short status message you compose in the plugin (default: failed-delivery summary or daily summary). Email-delivery providers (configurable in Settings → Connections) SendGrid (by Twilio) * Service: https://sendgrid.com * When data is sent: every WordPress email when SendGrid is the active connection, plus on test-email click. * Endpoint: https://api.sendgrid.com/v3/mail/send * Privacy Policy: https://www.twilio.com/en-us/legal/privacy * Terms of Service: https://www.twilio.com/en-us/legal/tos Mailgun (by Sinch) * Service: https://www.mailgun.com * When data is sent: same as above, but to Mailgun. * Endpoint: https://api.mailgun.net/v3/{domain}/messages (US) or https://api.eu.mailgun.net/v3/{domain}/messages (EU). * Privacy Policy: https://www.mailgun.com/legal/privacy-policy/ * Terms of Service: https://www.mailgun.com/legal/terms/ Amazon SES (AWS Simple Email Service) * Service: https://aws.amazon.com/ses/ * When data is sent: same. * Endpoint: https://email.{region}.amazonaws.com/v2/email/outbound-emails (region you select). * Privacy Policy: https://aws.amazon.com/privacy/ * Terms of Service: https://aws.amazon.com/service-terms/ Brevo (formerly Sendinblue) * Service: https://www.brevo.com * Endpoint: https://api.brevo.com/v3/smtp/email * Privacy Policy: https://www.brevo.com/legal/privacypolicy/ * Terms of Service: https://www.brevo.com/legal/termsofuse/ SparkPost * Service: https://www.sparkpost.com * Endpoint: https://api.sparkpost.com/api/v1/transmissions * Privacy Policy: https://www.sparkpost.com/policies/privacy/ * Terms of Service: https://www.sparkpost.com/policies/tou/ Postmark * Service: https://postmarkapp.com * Endpoint: https://api.postmarkapp.com/email * Privacy Policy: https://postmarkapp.com/privacy-policy * Terms of Service: https://postmarkapp.com/terms-of-service Elastic Email * Service: https://elasticemail.com * Endpoint: https://api.elasticemail.com/v4/emails * Privacy Policy: https://elasticemail.com (linked from the site footer; Elastic Email does not publish a stable deep-link URL) * Terms of Service: https://elasticemail.com (linked from the site footer; Elastic Email does not publish a stable deep-link URL) SMTP2GO * Service: https://www.smtp2go.com * Endpoint: https://api.smtp2go.com/v3/email/send * Privacy Policy: https://www.smtp2go.com/privacy/ * Terms of Service: https://www.smtp2go.com/terms/ Netcore Email API (formerly Pepipost) * Service: https://netcorecloud.com * Endpoint: https://emailapi.netcorecloud.net/v5/mail/send * Privacy Policy: https://netcorecloud.com/privacy-policy * Terms of Service: https://netcorecloud.com (request the latest terms via the contact form on the homepage; Netcore does not publish a stable terms-of-use URL). SMTP.com * Service: https://www.smtp.com * Endpoint: https://api.smtp.com/v4/messages * Privacy Policy: https://www.smtp.com/policies/privacy-policy/ * Terms of Service: https://www.smtp.com/legal/terms/ SocketLabs * Service: https://www.socketlabs.com * Endpoint: https://inject.socketlabs.com/api/v1/email * Privacy Policy: https://www.socketlabs.com/legal/privacy-policy/ * Terms of Service: https://www.socketlabs.com/legal/ Moosend (by Sitecore) * Service: https://moosend.com * Endpoint: https://api.moosend.com/v3/ * Privacy Policy: https://moosend.com/privacy-policy/ * Terms of Service: https://moosend.com/terms/ SendLayer * Service: https://sendlayer.com * Endpoint: https://console.sendlayer.com/api/v1/email * Privacy Policy: https://www.sendlayer.com/privacy-policy/ * Terms of Service: https://www.sendlayer.com/terms-of-service/ Mailjet (by Sinch) * Service: https://www.mailjet.com * Endpoint: https://api.mailjet.com/v3.1/send * Privacy Policy: https://sinch.com/legal/privacy-notice/ * Terms of Service: https://sinch.com/legal/ MailerSend * Service: https://www.mailersend.com * Endpoint: https://api.mailersend.com/v1/email * Privacy Policy: https://www.mailersend.com/legal/privacy-policy * Terms of Service: https://www.mailersend.com/legal/terms-of-use Mandrill (by Mailchimp) * Service: https://mailchimp.com/developer/transactional/ * Endpoint: https://mandrillapp.com/api/1.0/messages/send.json * Privacy Policy: https://mailchimp.com/legal/privacy/ * Terms of Service: https://mailchimp.com/legal/terms/ Resend * Service: https://resend.com * Endpoint: https://api.resend.com/emails * Privacy Policy: https://resend.com/legal/privacy-policy * Terms of Service: https://resend.com/legal/terms-of-service Zoho ZeptoMail * Service: https://www.zoho.com/zeptomail/ * Endpoint: https://api.zeptomail.com/v1.1/email * Privacy Policy: https://www.zoho.com/privacy.html * Terms of Service: https://www.zoho.com/zeptomail/terms.html Microsoft 365 / Outlook (Microsoft Graph API and SMTP) * Service: https://www.microsoft.com/microsoft-365 * Endpoint (API): https://graph.microsoft.com/v1.0/users/{user}/sendMail (OAuth token from https://login.microsoftonline.com/{tenant}/oauth2/v2.0/token) * Endpoint (SMTP): smtp.office365.com:587 * Privacy Policy: https://privacy.microsoft.com/en-US/privacystatement * Terms of Service: https://www.microsoft.com/en-us/servicesagreement/ Gmail / Google Workspace (Gmail API and SMTP) * Service: https://workspace.google.com * Endpoint (API): https://gmail.googleapis.com/gmail/v1/users/me/messages/send (OAuth token from https://oauth2.googleapis.com/token) * Endpoint (SMTP): smtp.gmail.com:587 * Privacy Policy: https://policies.google.com/privacy * Terms of Service: https://policies.google.com/terms Notification channels (configurable in Settings → Alerts) These services are contacted ONLY when a notification channel is enabled AND a delivery failure (or daily-summary) event triggers an alert. The data sent is the short status text shown in the plugin’s alert preview. Telegram (Bot API) * Service: https://telegram.org * When data is sent: when a Telegram channel is enabled, a failed-delivery alert or daily-summary alert is generated. * Endpoint: https://api.telegram.org/bot{token}/sendMessage * Privacy Policy: https://telegram.org/privacy * Terms of Service: https://telegram.org/tos Pushover * Service: https://pushover.net * Endpoint: https://api.pushover.net/1/messages.json * Privacy Policy: https://pushover.net/privacy * Terms of Service: https://pushover.net/terms Slack (Incoming Webhooks) * Service: https://slack.com * Endpoint: the webhook URL you paste (https://hooks.slack.com/services/…). * Privacy Policy: https://slack.com/trust/privacy/privacy-policy * Terms of Service: https://slack.com/legal Discord (Webhooks) * Service: https://discord.com * Endpoint: the webhook URL you paste (https://discord.com/api/webhooks/…). * Privacy Policy: https://discord.com/privacy * Terms of Service: https://discord.com/terms Microsoft Teams (Incoming Webhooks) * Service: https://www.microsoft.com/microsoft-teams/ * Endpoint: the Teams webhook URL you paste. * Privacy Policy: https://privacy.microsoft.com/en-US/privacystatement * Terms of Service: https://www.microsoft.com/en-us/servicesagreement/ Google Chat (Incoming Webhooks) * Service: https://chat.google.com * Endpoint: the Google Chat webhook URL you paste. * Privacy Policy: https://policies.google.com/privacy * Terms of Service: https://workspace.google.com/terms/premier_terms.html Custom Webhook * When data is sent: when a custom Webhook channel is enabled and an alert is generated, a JSON payload is POSTed to the URL you paste. * Endpoint: the URL you paste. * Privacy Policy / Terms: governed by the operator of the URL you provide. Bundled third-party libraries (no network call) Chart.js (https://www.chartjs.org) — bundled locally at assets/js/chart.umd.min.js (v4.5.0). Used to render the email-stats chart on the dashboard. Loaded entirely from your own server; no CDN call is made. Privacy Policy SendForce Mail Relay stores the following data in your WordPress database: Email logs (if logging is enabled): recipient email address, subject, headers, email body (optional), sent status, error messages, and timestamps. Email queue (if queue is enabled): same data as above, plus retry attempt count and next retry time. Plugin settings: your SMTP host, port, username, and encrypted password or API key. Email body logging can be disabled in Settings > Queue & Logging. Log entries are automatically deleted after the configured retention period (default: 30 days). All data is deleted when the plugin is uninstalled. We recommend adding a note to your site’s privacy policy if you log email content, informing users that outgoing email metadata may be stored.

Adds a simple, no-fuss SMTP settings to your WordPress installation that lets you define custom settings, which is especially useful for hosts with no control over the php mail functionality. If logging is enabled, a new segment in the settings panel will show up with a 30-day overview of recent emails, and will automatically prune older logs. Please see the FAQ if you want a more permanent solution. For more information, please see the project wiki on GitHub. Environment and constant overriding (optional) This plugin will prefer environmental and constant-stored values over the plugin-saved equivalent settings, making it easier to use this plugin via deployment. These can be either stored in your systems env setup, or in wp-config.php as define( 'SEE_BELOW', 'your_value_here' );. Accepted Parameters SMTP_HOST (string) Mail server hostname. SMTP_PORT (integer) Port address (usually 25, 465 or 587). SMTP_AUTH (integer, 1 or 0) Pass below credentials to your mail server. SMTP_USER (string) The mail username for this account. SMTP_PASS (string) The password for the mailer account. SMTP_FROM (string) Enforce all emails come from this email address. SMTP_FROMNAME (string) Enforce all emails to have a certain email name. SMTP_SEC (string) Use a particular email security method (accepts ‘def’ (default), ‘ssl’, ‘tls’ and ‘off’). SMTP_NOVERIFYSSL (boolean) Disable validation of the SMTP server certificate (not recommended). SMTP_LOG (boolean) Controls the logging capability and visibility. SMTP_DISABLE (boolean) Disables the mailer. They will still be logged if enabled, but won’t send out. It is recommended to store at least SMTP_PASS in your wp-config.php file (with the correct file permissions set). If the openssl extension is available, the plugin will attempt to encrypt the password in the database.