The Queue That Never Stopped

Emails were failing. That part was expected — broken SMTP credentials during a migration. What wasn't expected: they never stopped failing.

Horizon dashboard: green. Workers: healthy. Redis: slowly growing. No alerts, no errors in the logs. Just a quiet accumulation of jobs that kept trying and trying and trying.

I only noticed because Redis memory didn't come back down after fixing the SMTP config. Something was still in there, chewing through retries. Thousands of them.

I assumed the queue would handle it. That's the deal: a job fails, retries a few times, lands in failed_jobs. You move on.

Unless the job is a Mailable.

When you dispatch a Mailable to a queue, Laravel wraps it in a job. That job's maxTries comes from the Mailable's $tries property. If you don't set it — and why would you, the docs barely mention it — it serializes as null.

Null doesn't mean "use the supervisor default." Null means "no limit." Horizon sees null and thinks: this job wants to retry forever. So it does.

Turns out it's a known bug. Laravel Horizon issue #1346. The supervisor's --tries flag gets ignored when the serialized job payload carries maxTries: null. The job's own declaration wins, and its declaration says: never stop.

Twenty-nine Mailable classes. Every single one without an explicit $tries property. Every single one potentially immortal.

The fix is almost insulting in its simplicity:

class WelcomeEmail extends Mailable implements ShouldQueue
{
    public int $tries = 2;
    public int $maxExceptions = 2;
}

Two properties. Twenty-nine files. That's it.

One initial attempt, one retry, then failed_jobs. The way I assumed it always worked.

I test it the way you'd test a mousetrap. Break the SMTP config on purpose. Dispatch one email. Watch Horizon. Two attempts. Failed job. Done. No ghosts in the queue.

Then I fix the other twenty-eight.

Three lessons, condensed:

1. Null is not "default." In serialized job payloads, null maxTries means unlimited. Your supervisor config is a suggestion, not a rule.
2. Green dashboards lie. Horizon showed healthy workers happily processing jobs that would never finish.
3. Framework defaults are not always sane. Laravel doesn't set $tries on Mailables. You have to. The docs won't warn you until you already have a fire.

The scariest bugs are the ones that look like normal operation. This one did — for weeks.