How to Resolve Outlook Proxy Server Security Certificate Issue?

Many users have recently started experiencing errors on Outlook while trying to establish a connection to their remote mail server, which is typically Exchange Online or Exchange Server. Such users are likely to have experienced “mail server timed out” errors and might have noticed that their mailbox synchronization has stopped unexpectedly. This error is more likely to have been observed on computers running Windows 7 and Windows 8.0, as these machines only support older protocols for connecting with the Exchange Servers. In this article, we will explain what users can do to resolve the Outlook proxy server security certificate issue.

What Causes the Mail Server Timeout Issue?

The failure of the Transport Layer Security (TLS) handshake is one of the primary reasons for the timeout error. The TLS is a cryptographic protocol is designed to provide secure communications designed to provide communications security over a computer network for applications such as email, instant messaging, voice over internet protocol (VoIP), and as the Security layer in Hypertext Transfer Protocol Secure (HTTPS). Client-server applications, such as Exchange Server and Outlook, use the TLS protocol to secure communication lines against eavesdropping and tampering. The client requests the server to set up a TLS connection.

A stateful connection is negotiated between the server and the client when the client presents a list of supported ciphers and hash functions to the server to establish a handshake. This process can fail due to various reasons, especially if the client and the server use different versions of the TLS protocol.

How to Enable TLS 1.2 in Outlook?

While most Windows machines have automatically been upgraded to Windows 10 (and Windows 11), some computers still run Windows 7 and Windows 8.0, on which only TLS 1.0 & 1.1 are supported. This might conflict with servers that have been upgraded to the TLS 1.2 standards. Here is what users can do to enable TLS 1.2 on Outlook.

  • The preferred solution is to update Windows to Windows 8.1, Windows 10, or later versions, that natively support TLS 1.2 for client-server communications over WinHTTP.
  • Install Update 3140245 to add TLS 1.1 and TLS 1.2 to the default secure protocols list for WinHTTP if users must remain on Windows 7 or earlier versions.
  • Enable TLS 1.2 for SChannel at the operating system level, update and configure the .NET Framework to support TLS 1.2. The registry keys should be set appropriately to ensure that strong cryptography has been configured on computers that communicate across networks with TLS 1.2-enabled systems.

Apps4Rent Can Help with Secure Email Access

Apps4Rent offers a wide range of communication and collaboration solutions. Our hosted Exchange Servers in top-tier SSAE 16 data centers have been upgraded to the latest version of the TLS protocol to ensure privacy and security. We can also offer Azure Virtual Desktops with Windows 7 to help users who need older versions access emails using Outlook. Alternatively, we can help businesses upgrade to Exchange Online available as standalone plans, or a part of the Office 365/ Microsoft 365 productivity suite. Call, chat or email our Microsoft-certified professionals available 24/7 for assistance on the Outlook proxy server security certificate issue.

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