Mailster Dummy Mailer is a Mailster delivery method for WordPress newsletter development and testing. It registers as DummyMailer under Mailster’s delivery settings so you can run campaigns, workflows, and send tests without delivering real email to inboxes.

Use it when you need to exercise Mailster on staging or locally: practice campaign flows, tune how statistics look, and avoid accidental sends to live subscribers.

This plugin requires the Mailster Newsletter Plugin for WordPress 4.0 or newer. It does not send mail through SMTP or a third-party ESP—sending and engagement are simulated on your site.

What you can simulate

Delivery without inbox delivery — Outgoing Mailster sends are marked successful or failed based on your configured rates; no real messages leave the server.
Open, click, unsubscribe, and bounce rates — Set target percentages so cron-driven simulation can produce campaign statistics that match your test scenario.
Success and campaign error rates — Control how often a simulated send succeeds versus failing with a campaign-level or subscriber-level error.
Optional admin notice — Show a clear warning on Mailster newsletter screens so you know Dummy Mailer is active.
Simulated client and IP data — During simulation, random client profiles and IPs can be used for engagement events.
Workflows — Compatible with Mailster 4.0+ campaign workflows (alongside finished, active, and paused campaigns).

Who it is for

Developers building or customizing Mailster sites
Agencies staging newsletters before go-live
Anyone who needs newsletter testing without a live ESP or real recipients

Important notes

Dummy Mailer is for development and testing, not production sending.
Simulation can use significant memory; 256MB of PHP memory (or more) is recommended.
Switch back to Simple, SMTP, or another Mailster delivery method before real campaigns. Deactivating this plugin resets the delivery method to Simple if DummyMailer was selected.

Learn more about Mailster delivery methods in the Mailster knowledge base.

Additional Info

This plugin requires the Mailster Newsletter Plugin for WordPress 4.0 or newer. It does not use a third-party email API; all simulation runs on your WordPress site.