How to Send an Email When an ACF Field Is Updated on a Post

Custom fields often carry the detail that matters — a price, a stock status, an event date, an approval flag. Zapify can watch one Advanced Custom Fields field on a post type and email you the moment it changes, showing the old value and the new one. It uses the A field is updated on a post trigger and the Send an email action.

What this automation does

The automation is one trigger plus one action:

• Trigger: A field is updated on a post (ACF_POST_FIELD_UPDATED, Advanced Custom Fields)
• Action: Send an email (WP_SEND_EMAIL, WordPress)

When someone saves a post and the field you chose now holds a different value, Zapify sends the email with the field's old and new value filled in.

Each changed field fires its own run, and a field that was saved with the same value it already had does not fire at all. A change made by other code calling ACF's update_field() function is not seen — only saves that go through ACF's own screens or forms are.

Before you start

• Advanced Custom Fields installed and active, with a field group assigned to the post type you want to watch.
• A working mail setup so WordPress can send email.
• The field you want to watch already exists, so you can pick it from the list.

How to build the automation

Step 1: Create a new automation

1. In the WordPress admin, go to Zapify → Automations.
2. Click Add New to open the builder.
3. Name it clearly, such as Alert when a product price changes.

Step 2: Add the "A field is updated on a post" trigger

1. Click Add Trigger.

2. Choose Advanced Custom Fields as the app.

3. Select A field is updated on a post.

4. Configure the trigger:

Field	Required	What it does
Post type	Yes	The kind of post that carries the field, such as Product or Event.
Post	No	Pick one specific post, or leave it as Any post to watch every post of that type.
Field	Yes	The ACF field to watch. The list shows the fields of the field groups that apply to the chosen post type. Choose Any field to react to every change.
Only when the new value is	No	Run only when the field is saved with exactly this value, for example Out of stock. Leave it empty to run for any change.

Step 3: Add the "Send an email" action

1. Click Add Action.

2. Choose WordPress as the app.

3. Select Send an email.

Step 4: Configure the email

For example, to alert a shop manager when a price changes:

• To: shop@example.com
• Subject: {{trigger:FIELD_LABEL}} changed on {{trigger:POST_TITLE}}
• Body: {{trigger:POST_TITLE}}: {{trigger:OLD_VALUE}} is now {{trigger:NEW_VALUE}}. Edit it: {{trigger:POST_URL}}

Step 5: Set the steps Live and save

Each trigger and action has its own Live / Off / Draft switch. A new automation starts as a Draft and does nothing until its steps are Live.

1. Set the trigger and every action to Live.
2. Click Save.

Step 6: Test it

Open a post of the chosen type, change the field and click Update. Then check the recipient inbox, or open Zapify → Logs to confirm the run. Saving the post again without changing the field should do nothing.

Tokens you can use

Token	What it holds
Post ID / Post title / Post type / Post URL	The post that was saved.
Post author ID	The author of the post.
Field label / Field name / Field key / Field type	Which field changed, and what kind it is.
New value (formatted)	The value as ACF would show it on the page, for example an image field or a post-object field as readable text.
New value (as stored)	The value exactly as ACF stored it.
Old value	The value stored before this save.

Conclusion

With the A field is updated on a post trigger and the Send an email action, a custom field becomes something you are told about instead of something you have to check. For a team chat message instead of an email, see posting to Slack when an ACF field changes, or use the field in the other direction with writing an ACF field when a comment is approved.

FAQs

Is this free in Zapify?

The Send an email action is free. The ACF trigger is part of the Advanced Custom Fields PRO integration and needs an active Zapify PRO licence.

Does it fire once per save or once per field?

Once per changed field. If one save changes three of the watched fields, you get three runs. Pick one Field in the trigger if you only want one email.

Why did nothing happen when I saved the post?

Check that the value really changed — a save that leaves the field as it was does not count. Also confirm the Post type, Post and Field match, that Only when the new value is is empty or matches exactly, and that the trigger and action are both Live.

Does it catch changes made from code or by another plugin?

Only saves that go through ACF's own screens or front-end forms. A plugin or theme that writes the value directly with update_field() does not fire it.

Which user is the run about?

The person who saved the post. If nobody is signed in, such as for a scheduled save, Zapify uses the post's author.

Do I need to write any code?

No. Everything is configured in the Zapify visual builder.