# `PhoenixKit.Users.WelcomeEmailWorker`
[🔗](https://github.com/BeamLabEU/phoenix_kit/blob/v2.55.1/lib/phoenix_kit/users/welcome_email_worker.ex#L1)

Sends one user's welcome email, after the confirmation that enqueued it has
committed. See `PhoenixKit.Users.WelcomeEmail`.

## Job args

    %{"user_uuid" => "<uuid>"}

## What a run does

  1. Nothing, when the welcome email has been switched off since, or the
     user is gone. A deactivated user (`is_active` false) gets nothing
     either, with a line in the log.
  2. Claims the account: one conditional `UPDATE` writes
     `welcome_email_sent_at` into `custom_fields` only where it is absent
     and the address is confirmed. No row updated means it was sent
     already, or the address is no longer confirmed — done.
  3. Builds the message, then hands it to the mailer.

## At most once

The mark is cleared — and the job retried — only when the message is known
not to have gone out: building it failed (rendering, a template, the
provider; raised, thrown or exited), or the mailer reported that it was not
sent (`{:error, reason}`). A raise or exit *during* delivery leaves it unknown
whether the message went out, so the mark stays, the error is logged and
the job is cancelled rather than retried. So is a node that dies between
the claim and the send: that welcome email is lost. Both are deliberate —
a missing welcome email is a smaller harm than a second one.

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*Consult [api-reference.md](api-reference.md) for complete listing*