WordPress Reference Articles

Definitions for WordPress email infrastructure: DMARC alignment, SPF flattening, the wp_mail pipeline, app passwords versus OAuth, the components of authentication and what each one actually checks. Each entry settles one term.

Transactional email and WordPress

Transactional email goes to one recipient following one action they initiated. Here is what WordPress core and WooCommerce send, and how the legal carve-out works.
Read More: Transactional email and WordPress

How Email Works: A WordPress Operator’s Reference

The five-stage delivery chain from wp_mail() to inbox, what the operator controls, and how SPF, DKIM, and DMARC work as a system.
The WordPress email FAQ

Answers to common WordPress email questions covering configuration, deliverability, authentication, and the tools involved.
WordPress.com vs WordPress.org Email: Who Owns the Sending Pipeline

On WordPress.com, Automattic owns the sending pipeline and domain. On WordPress.org, the operator does. Every email behaviour difference follows from that.
The SMTP Field Manual

The SMTP Field Manual catalogues real-world bounce messages from major mailbox providers and spam filters – the lookup step in WordPress bounce diagnosis.
wp_mail Hooks Reference: Every Email WordPress Core Sends

Every email WordPress core sends and every wp_mail hook (wp_mail_failed, phpmailer_init, pre_wp_mail) with the filters that control each one.
WordPress Email Queues: When You Need One and When You Don’t

wp_mail() sends email synchronously – every call blocks the PHP process until SMTP completes. A queue decouples sending from the page request. Here’s when that matters.
Email service webhooks in WordPress: events, verification, retries

How ESP delivery-status webhooks work in WordPress: what Postmark, Mailgun, SendGrid, SES and Mailjet send, how to receive them, and how to verify them.
Less Secure App access: what replaced it, when it shut down, and what to do now

Google’s Less Secure App access ended: consumer Gmail 30 May 2022, Google Workspace 1 May 2025. The three replacements: OAuth, App Passwords, or switch provider.
How to set up Postman API platform as an OAuth client

Configuring Postman as an OAuth 2.0 client against Microsoft Graph or any IdP: redirect URI, PKCE, and token reuse details that trip up most setups.