WP Mail Manager

The problem

A growing WordPress store had thousands of registered users but no way to reach them outside WooCommerce order emails. Every promotional campaign needed a developer, a third-party SaaS account, and a manual export of the user list, which also meant handing a customer database to an outside service.

Sending it yourself has two failure modes that only appear at scale. Blast the whole list in one go and shared-hosting SMTP throttles or drops the run, the domain picks up a reputation hit, and nobody knows how far it got. Retry after a crash and the people who already received the message get it again, because "who has been sent this" was never recorded anywhere.

Before → After

How it works

1. Audiences are categories. Subscribers belong to categories, campaigns attach to categories, and both relationships are many-to-many, so one campaign can target several segments and a subscriber can sit in several without duplication.
2. The queue is derived, not stored.Pending recipients are computed by joining subscribers against delivery records and keeping the rows where no delivery exists. "Who still needs this" is therefore a consequence of the data rather than a flag somebody has to maintain, which is what makes an interrupted run resume exactly where it stopped, and makes sending the same campaign twice to the same person impossible.
3. Cron paces the send.A custom interval controls how often a batch goes out, a batch size controls how many, and a pause between messages keeps the run inside the host's SMTP rate limit instead of firing a burst that gets the domain flagged.
4. Every send is recorded. Each delivery writes its outcome, so the admin table can report pending, sent and failed per campaign without a separate log.
5. Test sends and a kill switch. A campaign can be sent to a single address first. Sending is disabled on activation, and a mail interceptor can log messages instead of delivering them, so a copy of the production database cannot email real customers.

Key features

• Category-based audience segmentation, many-to-many with campaigns
• Derived pending queue: resumable, and no recipient is served twice
• Cron dispatch with configurable interval, batch size and inter-message pause
• Per-campaign pending / sent / failed statistics
• Test send to a single address before launching
• Sending disabled by default; mail interceptor for non-production copies
• HTML and plain-text campaigns with per-campaign headers and sender
• Bulk assignment of existing users to a new category on creation

Installation

1. Upload the plugin folder to /wp-content/plugins/ and activate it
2. Let activation create the campaign, category and delivery tables
3. Open Mail Manager, create a category, and attach a campaign to it
4. Set the cron interval, batch size and pause to match your SMTP limits
5. Send a test message, then enable sending: it is off until you turn it on