Contact form 7 not showing success message: why

Contact Form 7 sends the form in the background and then writes one line into an empty box under the fields. When that line never appears, the visitor cannot tell whether the message left. Some visitors press Send again, so the owner may receive two copies while the visitor still sees no confirmation. The owner checks the inbox, sees the mail arrived and concludes the form is fine. A theme, a caching plugin or a redirect rule can empty the box without touching the mail at all.

• After Send, inspect the reply box and read its class. It names the status the plugin recorded.
• Check your host's mail log for the minute you pressed Send. A failed send can leave an entry there.
• Look in the console for a script error on the page, and confirm the plugin's script is loaded.
• Search the theme's stylesheet for the reply box class. A display none rule hides the message.
• Remove any redirect or thank-you page rule, then send once and see whether the box fills.

The first is mail. The form sends the message to your server, the server hands it to your mail system, and if that hand-off fails, the plugin records an error status and writes an error line where the thank-you should be. Hosts sometimes block the default mail function, so the message never leaves the server. The plugin cannot show a thank-you for a message it failed to hand over.

The second is a script that did not run. Contact Form 7 uses its own JavaScript to send the form in the background and fill the reply box. If a caching or minify plugin delays or combines that script, or a page builder replaces the form output with its own, the form can send with the reply box never filled. A stale cached copy of the page can also carry an old copy of the form's script.

The third is hiding. A theme stylesheet can hide the reply box, and a redirect or thank-you page rule can send the visitor away before the line appears. In both cases the mail arrives, the visitor sees nothing, and the owner concludes the form works. A redirect that fires on every send, not only on success, hides a failure line in the same way.

After Send, open the browser inspector and find the element whose class begins with wpcf7-response-output. That is the box under the form, and its classes say what the plugin recorded. A success class with an empty box points at CSS or a redirect. An error class points at a field or the mail step. If the box is missing from the page entirely, the form was rendered without the plugin's markup, which points at the theme or the page builder.

Read the console and the network tab at the same moment. A failed request to the form's endpoint means the page never reached the plugin. A successful request with an empty box means the reply came back and the page did not show it, which points at a script or a stylesheet. Note which of the two you see before you change anything.

Start the visitor on the contact page with the task of asking one question. It fills in the fields, presses Send and waits for the reply box to change. The report records what the box showed: a thank-you line, a line under one field, or nothing at all, along with any failed request or script error on that step and a screenshot.

Run it on a laptop and on a phone, because a theme can hide the box at one width only. The test does not read the mail log or your inbox, so it cannot say whether the message reached you. Check that in your mail settings and your own inbox after each run, then run the visitor again to see the reply box change.

Plugin and theme updates change the scripts and the stylesheet that fill the reply box, so the line can go missing after a routine update. Rerun the same visitor after each change, on a laptop and a phone, and check every preview deploy before it goes live. Owners whose site sits behind a password add the password to the run, so the visitor reaches the form the way a real customer would.