how do I select items based on properties of subitems?

Hello,
I’m relatively new to applescript and using Outlook 2015 (or 2016) for Mac.
In Apple Script, I was able to do things I was able to do with Apple Mail.
With Apple Mail I was able to do the following to select messages based on the sender:


set staledate to (current date) - (50 * days)

tell application "Mail"
	-- display dialog "Mail App selected"
	with timeout of 1500 seconds
		set msgs to every message of mailbox "Inbox" of account "Exchange" whose sender is equal to "root@example.com" and date received is less than staledate
	end timeout
	-- display dialog "Mails from root@rta.be selected"
	set MessageCount to 0
	repeat with aMsg in msgs
		-- ...
	end repeat
end tell

But in outlook for mac, the sender is an object itself splitter in three properties: {type, address, name}
Does anybody have an idea on how to make the same thing as in Apple Mail?
I did try with embedded (get sender), (extract … from…), …
but always end up with either a syntax error, either no exploitable results.
As the mailbox contains mores than 16Gb of data, in more than 30 folders and subfolders, I can’t make a first selection based on the staledate, and then iterate thru each message.

Thanks in advance for your valuable help!

Pascal