Microsoft has set the official retirement date for the insecure Transport Layer Security (TLS) 1.0/1.1 protocols in Office 365 starting with October 15, 2020. The effect of this change for end-users is expected to be minimal. Microsoft advises against using older versions of the insecure protocols. Users of the following clients are advised to update to the latest versions as they are known to be unable to use TLS 1.2+. Microsoft also provides a whitepaper with guidance on how to remove.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-will-disable-insecure-tls-in-office-365-on-oct-15/