Contact Form 7 reports a failure when trying to send the secondary email (Mail 2). The error indicates the SSL certificate presented by the SMTP server did not pass verification.
The verification step checks the certificate is signed by a trusted authority, it is still valid, and the hostname matches the certificate. If any of these checks fail, PHP aborts the TLS handshake and the mail is not sent.
Typical triggers include an expired or self‑signed certificate, a missing intermediate in the chain, a mismatch between the SMTP host name used in the form and the name on the certificate, or an outdated CA bundle on the web server.
When the PHP OpenSSL library is unable to locate a current list of root certificates, it treats the server’s certificate as untrusted. The same result occurs if the server requires SNI and the client does not provide the correct hostname.