Microsoft recently released a change notice about email accounts, which will be on December 10, 2022, to disable POP3 and IMAP4 TLS 1.0 / 1.1.
The email notification indicates that starting December 10, 2022, Office 365 will begin to phase out Transport Layer Security (TLS) 1.0 and 1.1 for POP3 and IMAP4, the standard communication protocols used to provide secure Web communications for POP3 and IMAP4, the client/server communication protocols used to receive email. Microsoft is mandating an upgrade to TLS 1.2 to provide enhanced encryption and to help ensure that you receive email more securely. Microsoft has discontinued TLS 1.0 and 1.1 for most Microsoft 365 services in a global environment.
As of December 10, 2022, POP3 and IMAP4 will not be able to connect with TLS 1.0 and 1.1. After that date, you will not be able to use POP3 / IMAP4 communication protocols to receive emails. To continue using POP3 or IMAP4 to access your email account, please upgrade/update your client to support TLS 1.2. Your email will not be deleted, but you will not be able to access email without upgrading your client. If you are unable to update/upgrade your email account, please do so.
If you are unable to update/upgrade the old client, Microsoft will provide an opt-in endpoint that allows continued connectivity via TLS 1.0/1.1. POP3 for older clients must be set to pop-legacy.office365.com and IMAP4 must be set to imap-legacy.office365.com. However, using older TLS versions is not as secure as TLS 1.2 in general, so it is recommended that you update and use TLS 1.2.