For SMTP the host should be *.mail.protection.outlook.com on port 25, .e.g.:

• <you mail>.mail.protection.outlook.com on port 25 to get it to work

The information is from: https://learn.microsoft.com/en-us/microsoft-365/enterprise/urls-and-ip-address-ranges?view=o365-worldwide

On Micosoft Azure, you need to enter a new registration under App Registrations. On this you will then find the:

1. Application ID (client)
2. Tenant ID = Directory ID (client) and
3. the Client Secret under Certificates & Secrets

The registered app must then be enabled for access via POP3 and SMTP via “API Permissions”. Under Add Permission and then the tab “APIs used by my organization” there select “Office 365 Exchange Online”. then “Application permissions” and there you will find POP and SMTP.

After that you have to do the following in the power shell:

Install-Module -Name ExchangeOnlineManagement
Install-Module -Name AzureAD
Install-Module Microsoft.Graph

Connect-AzureAD -TenantID <Ihre ID>

Connect-ExchangeOnline -Organization <Ihre ID>

 
# prüfen
Get-AzureADServicePrincipal -SearchString "<Display name of your application id>"

$MyApp = Get-AzureADServicePrincipal -SearchString "<Display of your application id>"

New-ServicePrincipal -AppId $MyApp.AppId -ServiceID $MyApp.ObjectID -Display "Sercie Principal for POP3 App"

Add-MailboxPermission -Identity "<login user>" -User $MyApp.ObjectId -AccessRights FullAccess