mail() function, called through the wp_mail() wrapper every plugin and theme relies on. It works fine in a demo. It falls apart the moment a real inbox provider gets involved, because a message sent through local mail() carries no authentication, no reputation, and no way for Gmail or Outlook to confirm your server is who it says it is. Password resets, order receipts, and quote requests routed this way are guesswork, not delivery.
WP Postman replaces that transport. It’s pre-installed and pre-activated on every WP Stratos site, and it gives you a working delivery path from the moment your site launches, plus the logging you need to prove (or disprove) that a specific message actually went out.
What it actually does
WP Postman doesn’t add one SMTP connection. It gives you eight, and they work in two structurally different ways:1
The native WP Postman relay
When you select the default WP Postman delivery method, the plugin skips SMTP entirely. It hooks
pre_wp_mail, builds a signed MIME message with PHPMailer locally, then hands that raw message to WP Stratos’s managed delivery API over an outbound HTTPS request. No SMTP handshake, no SMTP port. This matters on hosts and networks that throttle or block outbound port 587/465/2525, since HTTPS on port 443 almost never is. It’s also why this is the fastest path to get working: paste one API key into wp-config.php (or add it remotely through Developer Settings if you’d rather not touch files directly) and mail starts flowing, no host or port lookup required.2
Every other delivery method
SMTP.com, Brevo, Mailgun, SendGrid, Gmail, and Other SMTP all configure PHPMailer’s native SMTP client through the
phpmailer_init hook, the same mechanism most SMTP plugins use. These are real SMTP connections to real SMTP hosts, authenticated with the credentials you provide.The eight delivery methods, at a glance
Every field on every panel, including which settings are safe to change freely versus which ones need a test send afterward, is documented on the Delivery Method Configuration page.
What gets recorded
Every send attempt, regardless of which method handled it, writes a row to a dedicated database table (wp_wpp_mail_log). That table tracks the recipient, sender, subject, delivery method, status, HTTP response code where applicable, error message on failure, and optionally the full message body. Nothing here depends on WordPress’s own transient or debug log, so the record survives independently of WP_DEBUG settings and doesn’t compete with anything else for log space. Retention is configurable from one day to forever, and body storage can be switched off entirely if you’d rather the database not hold copies of message content. The full breakdown of the log screen, including the difference between Sent and Delivered, is on the Email Logs page.
Finding your way around
WP Postman adds one sub-level admin menu item with five tabs (Settings → WP Postman):WP Postman is a WP Stratos managed plugin. If you deactivate it, it reactivates automatically the next time it receives an update, the same behavior as Aero and WP Stratos Environment. See Plugin Reactivation if that’s unexpected.
Where to go next
Delivery Method Configuration
Every field, every panel, and which settings are safe to change without testing.
Email Logs
Read delivery status correctly, tell a bounce apart from a misconfiguration, and manage log retention.
Email Delivery Troubleshooting
Diagnose authentication errors, spam filtering, connection timeouts, and SPF/DKIM problems.