Unable to automate sending of email from remote Windows 10 desktop at startup (via Task Scheduler)

When Windows 10 remote desktop is rebooted, Task Scheduler (set up for execution when user is logged on or not) saves a file and sends an (empty) email.

The email sending does not work after reboot. It works only when launched manually or triggered by user from Task Scheduler.

I suspect it is related to state into which the machine is rebooted - it never really recovers user session. Could it be related to control against unattended sessions? https://support.microsoft.com/en-us/topic/considerations-for-server-side-automation-of-office-48bcfe93-8a89-47f1-0bce-017433ad79e2

I thought it can be be worked around by automated logon. Modifying the registries following https://learn.microsoft.com/en-us/troubleshoot/windows-server/user-profiles-and-logon/turn-on-automatic-logon however did not work and it in principle exposes credentials - desktop is used by several users.

Edit: sample python code which works when launched manually from Task Scheduler but not when launched by Task Scheduler at startup.

import win32com.client as win32
from datetime import datetime
o = win32.dynamic.Dispatch('Outlook.Application')
Msg = o.CreateItem(0)
Msg.To = "name@mail.com"
Msg.Subject = datetime.now().strftime('%Y%m%d-%H%M%S')
Msg.Send()

Task Scheduler is a service, and Outlook cannot be used from a service, even if the user identity is that of an interactive user. Outlook needs a local user with configured Outlook profile to be logged in.