How email works

Nothing is sent unconfirmed

Someone ticks the box, and a subscription is written with the status pending. It does nothing until they click the link in a confirmation email. Until then no notification is ever sent to that address.

The confirmation waits for the comment

For a subscription made with a comment, the confirmation email is not sent until the comment is approved.

This is deliberate. Without it, anybody could post a comment carrying somebody else's address and have your site email them on demand. WordPress holds first-time commenters by default, so on a quiet site most subscriptions sit waiting for a moment.

If a subscription seems stuck, Comments → Subscriptions says which of the two states it is in:

• no confirmation sent yet — usually the comment is still in moderation
• confirmation sent, waiting for the link — the mail went out, the reader has not clicked

There is a Send confirmation now action for pending subscriptions, for when you know the person is genuine and do not want to wait.

Confirmation links last 48 hours (happy_comments_confirmation_lifetime) and work once.

Sending happens after the response

The confirmation is sent at the very end of the request, after the page has already been handed back to the reader. So a slow mail server should not cause any noticeable delays.

Where the server cannot release the connection early — anything that is not PHP-FPM or LiteSpeed — it falls back to a scheduled job instead, so the reader never waits on the mail transport. A scheduled event is also kept as a fallback in both cases, and dropped once a send succeeds.

Notifications about new comments are always queued, in batches of 50.

What is never notified

• Comments on posts that are not published, or are password-protected
• Comments older than 24 hours, which is how imports and migrations are told apart from real activity
• Pingbacks and trackbacks
• The comment's own author, about their own comment
• Anyone already sent a notification about that comment

There is also a cap of 100 comments queued per request, so approving a thousand held comments does not turn into a thousand sends at once.

Unsubscribing

Every notification carries a link, and these headers:

List-Unsubscribe: <https://example.com/happy-comments/unsubscribe/42/…/>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

which is what makes the unsubscribe button in Gmail and Apple Mail work.

Opening that link in a browser shows a confirmation page with a button. It never unsubscribes on its own, because link scanners and mail gateways follow every URL in an email — a link that acted on being opened would unsubscribe people who never clicked anything.

Unsubscribing keeps the row, marked unsubscribed. It is the record of the opt-out; deleting it would let the next comment from that address resubscribe them as though it never happened.

Changing the wording

There is no template editor. Subjects and bodies go through filters — see Hooks — and every mail gets the same set of variables:

All mail: site_name, site_url, subscriber_email, subscription_id, subscription_type, post_id, post_title, post_url, unsubscribe_url

Confirmation adds: confirm_url, confirm_expires_at

Notifications add: comment_id, comment_author, comment_content, comment_url, comment_date

These names are fixed. File-based templates are planned, and once they ship these become something themes depend on.