Is it possible to disable IDLE/PUSH notifications on a per user basis?

I am not familiar with how IDLE works but receiving instant notifications of email is very very unproductive and really getting on my nerves as I just spend all day replying to new emails because when I finished some, nw ones come in. Its a known issue with email.

In my email clients (both Postbox and Mac Mail) I have disabled all the boxes that would fetch email. Even in Postbox there is a setting to be notified as soon as email comes in, and I have disabled it, but it still alerts me right away. Postbox told me IDLE is enabled in the core system and I cant turn it off which I find unbelievable. They used to have a box to disable it (although dont think it worked anyway).

All I want to do is access my email client all day, because thats where my tasks are, and reply to emails, or send new ones, BUT NOT download any new email until I click to download email. But as soon as I click into my Inbox or send an email I get all new email. I guess its IDLE. If I go offline for my email its OK, but when I go online to send an email, all new email is downloaded.

I wondered if there is a setting on the server to disable IDLE per user?