In this day and age having an on-premise Active Directory is not mandatory, especially if you are a small and/or new organization. Most of the services will be in Microsoft 365 anyways, so why bother maintaining local AD?
If you have an Azure Active Directory Tenant, users are allowed to join Windows 10 devices to the AAD domain by default.
In the AAD Portal, under Devices > Device Settings, settings can be adjusted to the organization's needs.
Joining the device is very easy. Just open the modern Settings app in Windows 10 > Accounts > Access work or school > + Connect. Then select Join this device to Azure Active Directory.
After logging off, any user that is a member of the tenant can log in with their email address/Azure AD account.
If you do hate passwords, this new feature from Microsoft might have solved that problem. With this feature, a user can send a push notification to Microsoft Authenticator, allowing access to any Microsoft 365 site without entering a password.
First of all, enable the so called "combined registration experience" in Azure AD under User settings.
Since I have a new tenant, the feature is automatically enabled for me.
After that, browse to Security > Authentication Methods > Policies. Select Microsoft Authenticator and enable it.
Users are not forced to use the new authentication method. They have to set that up themselves at https://aka.ms/mysecurityinfo.
Select Authenticator App as the method.
Download Microsoft Authenticator on the mobile phone.
Scan the QR code shown there.
Inside the Microsoft Authenticator app, select "Set up phone sign-in" and follow the wizard.
Now, upon logging in, you can select "User an app instead". This will trigger a notification on the phone app.
Getting started with Microsoft 365/Exchange Online in 2021 is very easy and relatively cheap (I am paying 5 bucks a month for one mailbox and some extra stuff, like 1 TB of OneDrive storage).
Roughly speaking, here are the high level steps from beginning to end:
Create your subscription
Add a custom domain
Verify the domain
Add DNS entries for MX, Autodiscover, and SPF
Create users
License users
Wait some minutes to see the mailbox in Exchange Online
Add account in Outlook
After creating your tenant (easy to do, you can also work with a third party, instead of buying the subscription directly off of Microsoft), open https://admin.microsoft.com and select Azure AD. Unser Custom domain names, add the organization's domain.
You verify the domain by adding a TXT record to at the root of your domain. You could also verify by MX record, but usually the organization has some sort of functioning mail product, so in a migration scenario that is not an option.
@ means the root of your domain. In my case ajni.it
Due to DNS Time To Live (TTL) and caching, this might take some time.
Back to the Microsoft 365 Admin Center, under Settings > Domains select the newly added domain and then Continue setup. Add the 3 records to your DNS.
Select Add your own DNS records. For mailing, Exchange Online and Exchange Online Protection records are needed.
After correctly adding DNS records for Exchange Online, add a user in Azure Active Directory and assign the license. Very straightforward. Set usage location to your organization's country. If you do not specify a usage location, licenses cannot be assigned to that user.
Under License the license can be assigned.
You could also choose to selectively assign certain products of the subscription. Either way one license will be burned.
It takes some minutes for the mailbox to show up in Exchange Online after assigning the license.
From now on, the account can be added in Outlook or accessed through Outlook on the Web https://outlook.office365.com
