After somebody submits a form they see a thank you page, with a title, a heading and text you write. It is the most attentive moment you will get from that customer, and most businesses waste it on one word.

What to put on it

• Confirm it worked. "We have your enquiry" — people genuinely wonder.
• Say what happens next, and when. "We will call you within one working day."
• Give them something to do while they wait — a phone number for anything urgent, a page worth reading.
• Set expectations honestly. If you will not reply until Monday, say so.

It is also a tracking page

The thank you page is where conversion tracking usually fires, so whoever manages your advertising will care about it existing and being reached — worth checking with them before changing how the form behaves.