Wp-calypso: Editor: Contact Form: add a customizable thank you message shown after a form is submitted

[designsimply]

Steps to reproduce:

1. Go to https://wordpress.com/ > My Sites > Pages.
2. Add a page with a form and publish it.
3. View the page and fill out and submit the form.
4. Observe whether there is a thank you message.

Result: after submitting a form, a "Message Sent (go back)" message is displayed as well as dump of all the form details submitted. A thank you message is not displayed, and there is not a way to add a custom thank you message in the contact form settings.

^{Seen at https://design5279.wordpress.com/contact-form-test/?contact-form-id=7618&contact-form-sent=11834&_wpnonce=a58aaf4a0f#contact-form-7618 using Firefox 58.0.2 on macOS 10.13.3.}

For reference, here is what the contact form settings currently look like:

^{Seen at https://wordpress.com/page/design5279.wordpress.com/7618 using Firefox 58.0.2 on macOS 10.13.3.}

/hat tip 🤠 @beaulebens for reporting this issue at p4k3M4-2uX-p2. #dogfooding #painpoint

[rachelmcr]

We've also had 23 reported support requests for a feature like this (internal ref: pKdGS-DZ-p2).

[alisterscott]

Would this belong in Jetpack since it's a contact form feature (that would be displayed on the front end of the site)?

[beaulebens]

It's probably a bit of both, and the code that powers Jetpack's Contact Form is the same code that powers WP.com's, so... it's one of those grey areas as to where we should actually track it :)

[alisterscott]

It's probably a bit of both, and the code that powers Jetpack's Contact Form is the same code that powers WP.com's, so... it's one of those grey areas as to where we should actually track it :)

Thanks, I also mean we'd want to make sure that all Jetpack sites would benefit as well

[stale[bot]]

This issue has been marked as stale and will be closed in seven days. This happened because:

• It has been inactive in the past 9 months.
• It isn't a project or a milestone, and hasn’t been labeled `[Pri] Blocker`, `[Pri] High`, `[Status] Keep Open`, or `OSS Citizen`.

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[stale[bot]]

This issue has been marked as stale and will be closed in seven days. This happened because:

• It has been inactive in the past 9 months.
• It isn't a project or a milestone, and hasn’t been labeled `[Pri] Blocker`, `[Pri] High`, `[Status] Keep Open`, or `OSS Citizen`.

You can keep the issue open by adding a comment. If you do, please provide additional context and explain why you’d like it to remain open. You can also close the issue yourself — if you do, please add a brief explanation.