About this plugin
Flex SMTP is the mail layer for the FLEX plugin suite. Flex Forms (and anything else that calls wp_mail() ) can leave SMTP credentials out of form settings. This plugin owns delivery: provider presets, SMTP or HTTP API, a test send, and a searchable log.
It is built for sites that already use FLEX plugins, and for hosts that block outbound SMTP ports 465/587. HTTP API sending uses WordPress wp_remote_post only — no vendor SDKs are bundled.
- Provider presets (Gmail, Microsoft 365, SendGrid, Mailgun, Amazon SES, and more)
- SMTP for every provider, or HTTP API for transactional services
- From email / name, default From replacement, and optional Force From
- One-click test email
- Searchable delivery log with retention
- Copies old Flex Forms SMTP options on first activate
Enable is off by default. Mail stays on the WordPress default mailer until you save a provider and turn Enable on.
CSS and JavaScript are loaded from this plugin only. There is no telemetry and no remote update checker.
Privacy
SMTP usernames, passwords, and API keys are stored in your WordPress database (leave a secret field blank when saving to keep the stored value). The optional email log stores recipient, subject, success/fail, and error text. Only administrators can view the log or settings.
When Enable is on, message content is sent to the SMTP host or HTTP API you configured. Flex SMTP does not send mail to any other remote service. See External services.
External services
This plugin connects to a third-party mail service only after an administrator chooses that provider, saves credentials, and turns Enable on (or clicks Send test). Until then, WordPress uses the default mailer. The plugin does not phone home.
What data is sent (every provider): From, To, Cc, Bcc, Reply-To, subject, body, and attachments from wp_mail(). SMTP also sends the saved username and password. HTTP API also sends the saved API key, and the secret, domain, or region when that provider requires them.
When data is sent: On each wp_mail() call while Enable is on, and when an administrator sends a test email.
Why: To deliver WordPress mail (password resets, form notifications, WooCommerce, and so on) through the account you already have with that provider.
Amazon SES
Amazon Simple Email Service delivers mail when Amazon SES is selected. com ). com.
The region is the one you pick in settings.
Service: Amazon SES
Terms of Service
Privacy Policy
Gmail / Google Workspace
com ) when that provider is selected. Uses an app password (OAuth is not included).
Service: Gmail
Terms of Service
Privacy Policy
Microsoft 365 / Outlook
com ) when that provider is selected. Uses SMTP AUTH and, when required, an app password.
Service: Microsoft 365
Terms of Service
Privacy Policy
Yahoo Mail
com ) when that provider is selected. Uses an app password.
Service: Yahoo Mail
Terms of Service
Privacy Policy
Zoho Mail
com ) when that provider is selected.
Service: Zoho Mail
Terms of Service
Privacy Policy
iCloud Mail
com ) when that provider is selected. Uses an app-specific password.
Service: iCloud
Terms of Service
Privacy Policy
SendGrid
net ) or the SendGrid HTTP API when that provider is selected.
Service: SendGrid
Terms of Service
Privacy Policy
Mailgun
net ) when that provider is selected. HTTP API also sends the Mailgun sending domain you enter.
Service: Mailgun
Terms of Service
Privacy Policy
Postmark
com ) or the Postmark HTTP API when that provider is selected. The API key is the Postmark server token.
Service: Postmark
Terms of Service
Privacy Policy
Brevo
com ) or the Brevo HTTP API when that provider is selected.
Service: Brevo
Terms of Service
Privacy Policy
Mailjet
com ) or the Mailjet HTTP API when that provider is selected. HTTP API also sends the Mailjet API secret.
Service: Mailjet
Terms of Service
Privacy Policy
SparkPost
com ) or the SparkPost HTTP API when that provider is selected. SparkPost is a Bird service.
Service: SparkPost
Terms of Service
Privacy Policy
SMTP2GO
com ) or the SMTP2GO HTTP API when that provider is selected.
Service: SMTP2GO
Terms of Service
Privacy Policy
Resend
com ) or the Resend HTTP API when that provider is selected.
Service: Resend
Terms of Service
Privacy Policy
Custom SMTP
Sends mail to the SMTP host you type in settings. That host’s own terms and privacy policy apply. Flex SMTP does not choose or document a third party for Custom.