docs.modx.pro
  1. Extras
  2. Sendex
  3. Interface
  4. Email queue

Email queue ​

The Email queue tab in Components → Sendex builds and sends letters to subscribers.

Building the queue ​

  1. Open Components → Sendex
  2. On Email queue select a newsletter in the dropdown and click Add to queue

Building the queue - 1

Building the queue - 2

Building the queue - 3

Each subscriber gets an sxQueue row with a snapshot of mail headers. The body is rendered at send time from the newsletter template (compact mode: empty email_body in the queue).

Duplicates are skipped by row hash.

Events: sxOnBeforeAddQueues (cancellable) and sxOnAddQueues.

Manual send ​

Sending

ActionDescription
SendSend selected rows
Send allSend the entire queue
Remove / Remove allDrop queue rows without sending

Manual send from the manager stops on the first error (stopOnError: true).

Single message pipeline ​

  1. Atomic claim: row gets claimed_at, attempts++, expires_at (+900 sec)
  2. Render body from template with newsletter, subscriber, user, profile placeholders
  3. Event sxOnBeforeQueueSend — plugin can cancel (row removed, no requeue)
  4. Send via PHPMailer
  5. Success — row deleted, event sxOnQueueSend
  6. Failure — claim released, event sxOnQueueSendFailed, retry on next run

After a batch — event sxOnQueueFlushComplete.

Claim and retry ​

ResultQueue rowEvent
SuccessdeletedsxOnQueueSend
BeforeQueueSend canceldeleted—
SMTP errorclaim released, retrysxOnQueueSendFailed
Plugin skip (false)deleted—

Parallel cron workers cannot send the same row twice — atomic DB claim.

Cron ​

Add a cron job from the MODX site root:

bash
php core/components/sendex/cron/send.php

Frequency depends on subscriber count and hosting limits. Default batch size: 100 emails per run.

Change the limit with system setting sendex_queue_limit — transport does not create this key; add it manually if needed. See System settings.

Example cron entry (every minute):

bash
* * * * * php /path/to/modx/core/components/sendex/cron/send.php

Cron uses the same pipeline as Send all, but does not stop on the first error and logs failures to the MODX log.

Manager send vs cron ​

Manager “Send to subscribers”Queue + cron
Build queueyesmanual or Add to queue
Sendimmediatelyon schedule
Stop on erroryesno
Batch limitall queue rowssendex_queue_limit (100)