Hidden field

A Hidden field is sent with every message and never shown, such as a campaign name or where the visitor came from.

[[source]]

Settings

Setting	What it does
Value	What it sends. It goes into mails and entries like any field.
Fill from	Takes the value from the visit instead: a URL parameter, a shortcode attribute, the page or the logged-in user. See Fields.
Name to read	The parameter, attribute or custom field to read. Empty: the field’s name.

A Hidden field has no style, classes, ID or attributes, since nothing is shown.

In the mail

[source] prints the value.

Example

Name the field utm_source and set Fill from to URL parameter. A visitor who comes from ?utm_source=newsletter sends newsletter with the message.

Visitors can change what a Hidden field sends, so never use one for prices or anything you trust. The Stripe and PayPal fields read a Hidden field’s saved value, not the sent one.