Resolving TLS Negotiation Error for Emails
To resolve the TLS Negotiation error when sending emails, especially when using an external DNS service that rewrites DNS records and proxies SSL to the mail server, follow these steps:
1. Identify the Correct Mail Server Hostname
Locate the hostname of your mail server in the welcome email from your shared hosting package. It will look similar to shared1.gnt.faastic.com.
2. Access Cloudflare DNS Settings
Log in to your Cloudflare or DNS provider account and navigate to the DNS settings section.
3. Update the MX Record
Find the MX record for your domain and update it to the correct mail server hostname identified in step 1.
4. Disable Cloudflare Proxy (Optional)
If any mail-related DNS records are proxied through Cloudflare, change their status to DNS only by clicking the cloud icon next to the record.
5. Save Changes
Save your DNS settings. Changes may take up to 24 hours to propagate.
6. Verify Configuration
After propagation, test sending emails to ensure the TLS Negotiation error is resolved.
By updating the MX record to point directly to your mail server's hostname and ensuring DNS records related to email services are correctly configured, you can resolve email sending issues caused by TLS Negotiation errors.
The above is a solution for following full error
TLS Negotiation failed: FAILED_PRECONDITION: starttls error (71): 8442728243200:error:10000417:SSL routines:OPENSSL_internal:SSLV3_ALERT_ILLEGAL_PARAMETER:third_party/openssl/boringssl/src/ssl/tls_record.cc:592:SSL alert number 47
Some technical background:
The occurrence of TLS negotiation errors, such as the "FAILED_PRECONDITION: starttls error (71)" when sending emails from Gmail to a mailbox, especially in the context of using Cloudflare instead of a direct DNS server, can be attributed to several key factors associated with how Cloudflare interacts with email traffic and DNS configurations. Understanding these factors requires an appreciation of the technical distinctions between Cloudflare's services and traditional DNS server functionalities.
Cloudflare is primarily designed to enhance website security and performance through a broad spectrum of services, including DDoS protection, web application firewalls, and content delivery network (CDN) capabilities. One of Cloudflare's hallmark features is its ability to act as a reverse proxy, sitting between a website's visitors and the hosting server. This setup allows Cloudflare to filter and manage incoming traffic for web requests, providing security and performance enhancements. However, this proxy service is tailored towards HTTP/HTTPS traffic and does not natively support SMTP, IMAP, or POP3 protocols used for sending and receiving emails.
When Cloudflare is used to manage DNS settings for a domain, DNS records such as A, AAAA, and CNAME can be proxied to leverage Cloudflare's security and CDN services. However, MX (Mail Exchange) records, which direct email traffic, cannot be proxied through Cloudflare in the same way. MX records must point directly to a mail server's IP address or a hostname that resolves to an IP address not proxied by Cloudflare. This is where the distinction becomes crucial: if Cloudflare is set to proxy all traffic, including that intended for the mail server by misconfiguration, it can disrupt email delivery because Cloudflare will not handle email protocol traffic as expected.
Furthermore, Cloudflare's SSL/TLS encryption services, which are part of its security offerings, can complicate email delivery if not correctly configured. Cloudflare provides SSL/TLS encryption for web traffic, but email services rely on their encryption protocols like STARTTLS. If there's a misconfiguration in how SSL/TLS certificates are applied, or if there's an attempt to proxy email traffic through Cloudflare, it can lead to errors in TLS negotiation. This happens because the encryption expectations between the sending and receiving servers do not match, causing the email server to reject the connection due to perceived security risks, such as the wrong type of encryption being applied or improper certificate validation.
In contrast, using a dedicated DNS server for email configurations avoids these complications. A DNS server that directly manages the domain's DNS records without acting as a proxy for traffic allows for precise control over MX records and direct, unaltered routing of email traffic. This direct management eliminates the risk of misconfiguration related to proxying and encryption services that are not suited for email protocols, ensuring that emails are sent and received without interference from intermediary security and performance layers not designed for email traffic.
In summary, while Cloudflare offers significant advantages for managing web traffic, its architecture and service offerings can inadvertently introduce complexities and challenges for email delivery. Understanding and correctly configuring DNS and MX records, while ensuring email traffic is appropriately routed outside of Cloudflare's proxying and encryption services, is essential to prevent TLS negotiation errors and ensure reliable email communication.
More information on cloudflare DNS and MX records can be found on: https://developers.cloudflare.com/dns/troubleshooting/email-issues/ .
