Background Queue Manager & Batch Dispatch

High-volume marketing broadcasts and transactional bursts should never block web requests or cause PHP timeout errors. MailFuz includes a dedicated Background Queue Manager that processes outgoing transmissions asynchronously using database-backed job workers.

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Queue Manager Architecture

The Queue Manager operates via an independent database ledger (wp_mf_queue) with state tracking:

flowchart TD
    A[Broadcast or Transactional Burst] --> B[Push Jobs into wp_mf_queue]
    B --> C[HTTP Request Returns Immediately to User]
    D[Background Worker / WP-Cron / WP-CLI] --> E[Fetch Batch of Pending Jobs]
    E --> F{Delivery Attempt}
    F -->|Success| G[Mark Job COMPLETED & Log Telemetry]
    F -->|Temporary Failure| H[Increment Retry Count & Schedule Exponential Backoff]
    H -->|Max Retries Exceeded| I[Mark Job FAILED & Quarantine]

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Accessing the Queue Manager

Navigate to WP-Admin → MailFuz → Queue Manager (admin.php?page=mailfuz-queue):

• Pending Dispatches: Total count of scheduled emails awaiting transport transmission.
• In-Progress / Processing: Jobs actively currently being dispatched by the active worker.
• Completed Transmissions: Total count of successfully transmitted messages.
• Failed / Error Jobs: Messages that encountered transport rejection after maximum retry attempts.

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Batch Controls & Throttle Configuration

Under MailFuz → Settings → General → Queue Processing:

Setting	Recommended Value	Purpose
Queue Batch Size	25 - 100 messages	Number of messages dispatched in a single worker cycle. Prevents hitting web host memory caps.
Worker Frequency	Every 1 to 5 minutes	Interval between automated execution cycles.
Max Retry Limit	3 attempts	Number of times a failed dispatch is re-attempted before marking as dead letter.
Throttle Delay	100ms - 500ms	Micro-pause between dispatches to adhere to provider rate limits (e.g., SES 14/sec).

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Execution Modes: WP-Cron vs. System Cron vs. WP-CLI

1. WordPress Default (WP-Cron)

• Executes whenever visitors browse your website.
• Suitable for small sites with moderate broadcast volume.
• Can be erratic if site traffic is low.

2. Server Cron (Recommended for Production)

• Disable virtual cron in wp-config.php:

  define( 'DISABLE_WP_CRON', true );

• Add a real Linux/cPanel crontab entry running every minute:

  * * * * * wget -q -O - https://yourdomain.com/wp-cron.php?doing_wp_cron >/dev/null 2>&1

3. High-Throughput WP-CLI Queue Runner

For large broadcasts exceeding 100,000 subscribers, run the native MailFuz queue daemon via command-line shell:

# Process next 100 queued items immediately
wp mailfuz queue process --limit=100

# Continuous daemon loop with sleep intervals
wp mailfuz queue daemon --sleep=2

# Inspect live queue metrics
wp mailfuz queue status

# Flush and retry all temporarily failed jobs
wp mailfuz queue retry-failed

Tip

When running the WP-CLI daemon under Supervisor or Systemd, thousands of emails can be dispatched per minute without consuming PHP-FPM web worker threads.