We need to support IMAP/POP OAuth 2.0 token based auth:
Accordingly to this post in the Microsoft Tech Community post, Microsoft will stop to support basic authentication for IMAP and POP protocols for Exchange Online by Oct/2020. The only way to authenticate in Exchange Online service for POP/IMAP protocols will be through OAuth 2.0 token based auth.
It may affect our customers that have IMAP/POP Jira Cloud external Mail Handlers configured pointing to this service.
In addition to the Microsoft post we already have another security issue related to that. Both issues may have the same solution. https://jira.atlassian.com/browse/JRACLOUD-73004