Solved Program starting on logon

I have a quick question regarding program running at log on. (maybe boot up. I don't know till I logon)

I do not have anything in the Startup folder.

I am using Windows 10 and in this instance Outlook 2007.

Whenever I shutdown in the evening, I religiously close all open programs first and then shutdown.
If I hit the shutdown before all programs are closed I get a 'Program Still Open' type message which isn't very often as I make sure programs are closed.
I have noticed on a couple of occasions where a program, usually Outlook 2007, will open when I log on.
Also I have Outlook empty the Deleted Items folder every time I close the program. This morning, yesterdays deletes were still there so it obviously had not closed.

So,
if Outlook was still open on PC shutdown, (I forgot to close it) I should have received a Program Still Open message?
if Outlook had not completely closed on PC shutdown (I did not forget to close it) I should have received a Program Still Open message and PC would wait for Outlook to complete closing?
if Outlook did completely close why did it not empty the Deleted Items folder?
if Outlook did completely close, why did it start up on logon?
Whether Outlook closed normally or abnormally why would it restart at logon?
Is something being held in memory/cache or whatever?

There is no performance problem, I just hate anomalies.

It has happened on other programs in the past, can't remember which off the top of my head, and I have just ignored it. This morning I woke in a pedantic mood and needed something to fix.

Thanks for the quick reply Vger.
"see if your win 10 is under selective startup " If you mean Load system services, then Yes it is.
"Go into services and un-select Outlook " Outlook is not listed. None of the Office progs are listed here
"this should stop that at login " Please note, it doesn't always start at logon, just once in awhile

Hi Rusty, I don't think so. The box is under the desk and I just reach under to turn on so not sure. But your point about sleep is worth considering. I don't have hibernate enabled. I'll need to monitor it over a few shutdowns to see what happens.

Okay, I did a couple of normal shutdowns and boot up worked correctly.

I then did a couple of shutdowns with programs still open. the first before Outlook had finished doing its thing and again with Outlook and Chrome still open.
Both occasions on boot Outlook opened and on the last occasion Chrome did not reopen.

So, if a program has not shut down completely, the PC goes into sleep mode instead of waiting for it to complete. I suppose that's in case of power failure but would be nice if it could differentiate between a normal and abnormal shutdown..

Well that's another problem solved. thanks for your help.