Microsoft is retiring basic authentication in October 2020 for new O365 customers and late 2021 for current customers. Currently to email through Office 365, we have to use SMTP Auth. The reason for the retirement is the vulnerability of basic authentication. I am requesting that emailing items such as EFTs meet Microsoft's new requirements. The announcement can be read here: https://techcommunity.microsoft.com/t5/exchange-team-blog/basic-authentication-and-exchange-online-april-2020-update/ba-p/1275508.