When connecting to an Office 365 mail server, the connection fails with an error that indicates it could not create a security context. The application had been working previously and the account credentials are valid.
When the application attempts to connect to a Microsoft Office 365 mail server, typically outlook.office365.com or a related domain, error code 12102 (0x80042F46) is returned. This error can occur with any of the SocketTools mail components or libraries using POP3, IMAP4 or SMTP to connect to an Office 365 Exchange server.
The error does not indicate a problem with the user account or credentials. It usually occurs when Microsoft's servers reject the secure connection. As of October 15, 2020 Microsoft has deprecated support for TLS version 1.0 and 1.1, and no longer supports those security protocols.
Applications which were developed using older versions of SocketTools which do not support TLS 1.2, or are running on older Windows platforms such as Windows XP and Windows Vista, will no longer be able to connect to Office 365 Exchange servers.
Because of this change, we only support connections to Office 365 servers on Windows 7 and later platforms, using the current version of SocketTools. If you have any questions about upgrading your project to the current version, please contact our technical support team.