Synchronisation?

I can select synchronisation every 10 minutes. My e-mail should be Push-mail right? I am using O365 so should i really change the settings or leave it as is? I want to receive mail quickly on my laptop or else i will answer it on my mobile phone.

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With IMAP, the Inbox is synced in real time, so PUSH IMAP.
With Exchange, the Inbox is synced every 1 minute.
You cannot change that.

The setting in your screenshot is for all other folders, as well as calendars and contacts.