What does Gmail SSL_connect error mean and how to fix it?

Email marketer from Stack Overflow explains that troubleshooting SSL errors can include checking your system's time and date settings, ensuring that you have the correct root certificates installed, and verifying that the server supports the encryption protocols and ciphers that your client is using.

Email marketer from ServerFault describes the "SSL connect error" indicates that the client is unable to establish a secure connection with the server. One of the first things to check is whether the client can resolve the server's hostname to an IP address using DNS. Also ensure the client can reach the server on the SSL port, and there are no firewall rules preventing the connection.

Email marketer from Reddit user suggests checking your firewall settings to ensure that outbound traffic on port 443 (HTTPS) is allowed. If you're using a proxy server, verify that it's configured correctly to handle SSL connections.

Email marketer from The SSL Store responds that the most common cause of the SSL connect error is an error with the SSL certificate itself. A fix is to regenerate your CSR, reinstall the certificate and ensure to install any necessary intermediate certificates.

Email marketer from Namecheap explains if the server is using Server Name Indication (SNI) to host multiple SSL certificates on a single IP address, ensure that the client supports SNI. Older clients or browsers may not support SNI, which can lead to SSL connection errors.

Email marketer from LinuxQuestions.org shares that a good practice is to check the server's error logs (e.g., Apache's error.log or Nginx's error.log) for more detailed information about the SSL connection failure. The logs can provide clues as to why the SSL handshake is failing, such as certificate errors or protocol mismatches.

Email marketer from freeCodeCamp details that causes of the SSL connect error include things like the target server rejecting the connection, issues with the browser such as incorrect settings or expired cache, and network related problems such as dropped packets.

Email marketer from Super User shares that common causes include incorrect server configuration (e.g., using an outdated SSL/TLS protocol or a weak cipher suite), client-side issues (e.g., not supporting the server's preferred SSL/TLS version), and network firewalls blocking the connection.

Email marketer from Ask Ubuntu explains if you are encountering an 'SSL connect error' while trying to access a website, it might be caused by an expired certificate on the server-side. Alternatively, the client might be missing the required Certificate Authority (CA) to verify the identity of the server.

Expert from Spamresource responds that SSL connection failures can occur during email sending due to misconfiguration, server issues, or network problems. Check server logs for specific error messages and verify SSL/TLS settings.

Expert from Email Geeks explains "Network fall down; go boom." is by far the most likely, judging just from the error message. That error is coming from your smarthost, not from google, and google tends to play nice with protocol.

Expert from Email Geeks explains TLS negotiation failed after STARTTLS.

Expert from Email Geeks shares if it's a one-time issue, blame it on a network glitch. If it recurs, check your TLS configuration on that smarthost to make sure it's compatible with modern standards.

Expert from Email Geeks confirms it's definitely not a block.

Documentation from OpenSSL explains that SSL_connect errors generally indicate a failure to establish a secure connection. Possible causes can include mismatched SSL/TLS versions, certificate validation problems, or network issues that prevent the handshake from completing.

Documentation from DigiCert responds that diagnosing SSL connection failures involves checking the server's SSL certificate for validity, ensuring that the correct intermediate certificates are installed, verifying that the server's hostname matches the certificate's Common Name (CN) or Subject Alternative Name (SAN), and making sure that the server is listening on the correct port (usually 443 for HTTPS).

Documentation from Google Support explains that SSL connection errors can occur when Gmail is unable to establish a secure connection with the recipient's mail server. This could be due to issues with the recipient server's SSL certificate or configuration.