Previously in Dynamics NAV2016, user was linked with office365 account and there was multi-factor authentication enabled. So user can login to NAV using office365 credential and 2FA which is secured login. Now Microsoft has upgrade TLS for office365 but did not upgrade the security feature on Dynamics NAV2016. For which we cannot use office365 account and 2FA anymore for NAV login. It's blocking the application. So it is required to disable office365 integration with NAV. Now we need to use simple NAV user ID and password to login to NAV and there is no multi-factor authentication. Is it secured way to login to Dynamics NAV? Is Dynamics NAV not Microsoft product? Microsoft upgrade security for one platform but did not upgrade security for another platform which are linked with each other. How Microsoft can do like this? And one more thing is there is no limitation for entering wrong password. Anybody can try unlimited times to break any password which is not logical also. Are we paying to Microsoft for unsecured service? We are looking for a proper secured solution immediately. We cannot leave our Dynamics NAV unsecured.