Free Posts with Extended Security Requirements
Google and Microsoft are tightening security requirements for their free email services, including Gmail, Outlook.com, Hotmail, and Live.com. In the short term, this can lead to unwanted effects when archiving with MailStore.
Both providers require the use of "Modern Authentication" when logging into free email services and require authenticated client applications. This change creates additional challenges for third-party vendors.
MailStore customers who archive emails from Gmail accounts are currently receiving a warning that the application is not authenticated. In some cases, new logins are also blocked. We are working to re-authenticate our application with an authorized Google test lab. Unfortunately, we cannot speed up this process. Therefore, we kindly ask affected customers to be patient for a few more days. It is expected that the application will work again without further changes to the affected systems.
Microsoft also announced that it will implement "Modern Authentication" on outlook.com, hotmail.com, and live.com using OAUTH 2.0. We are also preparing a solution for this and expect it to be available in one of the next software versions. However, we cannot ignore the possibility that Microsoft's freemailers may also temporarily experience similar difficulties.
Source: Freemailers with Extended Security Requirements - MailStore