Скачать с ютуб Resolving MailKit Connection Issues to MailEnable SMTP Server Caused by SSL Certificate Errors в хорошем качестве

Resolving MailKit Connection Issues to MailEnable SMTP Server Caused by SSL Certificate Errors

Learn how to fix MailKit connection problems with MailEnable SMTP due to SSL certificate mismatches. Find step-by-step guidance tailored for ASP.NET Core applications. --- This video is based on the question https://stackoverflow.com/q/74877737/ asked by the user 'dpant' ( https://stackoverflow.com/u/313935/ ) and on the answer https://stackoverflow.com/a/74919389/ provided by the user 'dpant' ( https://stackoverflow.com/u/313935/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: MailKit used by ASP.NET Core web application fails to connect to MailEnable SMTP server because of the SSL certificate Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- Troubleshooting MailKit Connection Issues with MailEnable SMTP If you've recently encountered issues sending emails from your ASP.NET Core web applications using MailKit with MailEnable, you're not alone. A common problem arises from SSL certificate mismatches, which can prevent successful SMTP connections. This guide will provide an in-depth explanation of the issue and outline the steps you can take to resolve it effectively. Understanding the Problem In this scenario, a web application hosted on a Windows Server 2012 R2 environment suddenly stopped sending emails. After some investigation, you might have encountered an error message resembling the following: [[See Video to Reveal this Text or Code Snippet]] Key Points: MailEnable Version: The server runs MailEnable Standard Version 10.34. SSL Certificates: Each ASP.NET Core web app has its own configured SSL certificate, while Plesk manages additional SSL/TLS certificates via Let's Encrypt. Error Specifics: The main error indicates that the connection is unsuccessful because the SSL certificate's host name mismatches the server's address. Breakdown of the Solution To diagnose and fix the issue, let’s explore the details further. The Root Cause The primary cause of the connection failure lies in the SMTP client code where the server's IP address is used: [[See Video to Reveal this Text or Code Snippet]] This approach is flawed because: Certificate Issuance: SSL certificates are issued for domain names, not IP addresses. Thus, connecting to the server's IP won't match the domain listed in any SSL certificate. Mail Server Operation: As several web applications are hosted with individual SSL certificates, it’s essential to use the correct domain name instead of relying on the server's IP. The Fix The solution is straightforward—replace the server's IP address with the correct domain name associated with the web application. For example: [[See Video to Reveal this Text or Code Snippet]] By modifying this line of code, you ensure that the connection matches the domain for which the SSL certificate has been issued. Additional Considerations Server Configuration: Ensure that the MailEnable server configuration is correctly set up. IIS and Plesk Settings: Regularly check the configuration settings in both IIS and Plesk to prevent similar issues in the future. Conclusion Troubleshooting MailKit connection issues can be complex, especially when SSL certificates are involved. However, understanding that certificates should match domain names rather than IP addresses can save significant time and frustration. By using the correct domain in your MailKit SMTP connection, you can resolve the connection error and ensure successful email delivery. If you encounter any further issues or need additional assistance, feel free to reach out for a more detailed examination of your specific configuration.