A successful form response is not an inbox-delivery receipt. A successful return from WordPress’s mail function means the sending method could process the request, not that the recipient received the email. 2
Check the mail configuration
Open Contact Form 7’s Mail tab and verify the recipient and sender. The plugin recommends a sender address on the website’s domain. The visitor’s address belongs in an appropriate reply-to field, rather than being used to impersonate an arbitrary sender. 1
For example, use an address you have actually configured, such as forms@yourdomain.example, and map the submitted email field to the reply-to setting. Do not copy an example address into a live configuration.
Follow one identifiable message
Submit a test with a unique subject. Check spam folders, bounce notices and the sending service’s log. If your provider offers authenticated SMTP or API delivery, verify that setup and its required domain authentication.
Random repeat submissions make the trail harder to follow. One timestamp, recipient and service response is more useful than ten reports that “it still fails”.
If the form never reaches its success response, you are investigating a different stage: the browser request or server-side processing. Changing mail settings alone is not a diagnosis for a form that never finishes submitting.
Related reading
WordPress maintenance and performance
