Hi computeronix,
As I understand it, you want to find a way to subscribe to planned maintenance notifications. If there is any misunderstanding, please correct me.
Currently, it is unavailable to subscribe Planned Maintenance Notification. When there's a need for maintenance downtime we'll schedule it and it will be announced in your Office 365 Portal. I believe that they'll try to make sure that all of such downtime occurs during non-business hours, but at the same time our system is designed in such a way as to not expose you to most of the maintenance, as we aim to keep the system up all the time.
If you have any questions or have additional information to add to your previous suggestion, I would suggest you submitting a feedback at support.microsoft.com/.../survey.aspx
Thanks for your understanding.
Best Regards,
Anna Shi