Is there a way to make MS Outlook download new mails only once an hour?

I think you can go to Tools – Send/Receive – Send/Receive Settings. Something like that? Maybe if you start there it will become obvious? Or, hopefully someone who knows better will answer here.

@JLeslie is correct.

Go there, then pick Define Send/Receive Groups. If you have multiple email accounts, you may add them separately or combined to a new group or groups with varying send/receive time ranges by picking “new” to create the additional group(s), then pick the accounts and set the send/receive time limit. It doesn’t hurt anything to leave the original send/receive time in All Accounts, but I select “edit” on it afterward and deselect the mail accounts added to the alternate group(s).

under Tools; Optioons;send/recieve group. Change the automatic send/receive to 60.