WordPress SMTP for Transactional Email

Why default WordPress mail fails

WordPress uses wp_mail() as an abstraction. On many hosts, that eventually uses local mail infrastructure with weak authentication and poor visibility.

For production transactional email, use authenticated SMTP relay or a provider plugin so mail is signed, logged, and trackable.

Postscale SMTP settings

Use port 465 only if the SMTP plugin requires implicit TLS.

From domain rules

Use a From address on a verified domain:

store@example.com

Avoid sending WooCommerce receipts from free mailbox domains such as gmail.com or outlook.com. Your store domain should pass SPF, DKIM, and DMARC alignment.

WooCommerce checklist

1. Verify the sending domain.
2. Configure SMTP credentials.
3. Send a password reset test.
4. Send a WooCommerce order test.
5. Check headers for SPF, DKIM, and DMARC pass.
6. Import suppressions from the old provider.
7. Keep customer-service reply handling stable.

For commerce-specific deliverability, see Postscale for e-commerce.

Webhook handling

WordPress does not need to process every event itself. A webhook handler can be:

1. A small custom plugin.
2. A REST endpoint in a companion application.
3. A queue worker that updates WordPress through the REST API.

Use idempotency so duplicate webhooks do not update the same order repeatedly.

References

• WordPress wp_mail documentation
• WordPress REST API handbook
• SMTP ports guide
• SPF, DKIM, and DMARC setup guide