How can I configure the Email app not to save sent messages on the Google server using IMAP? Device: Nexus 4
Android: 4.2.2

I am using the default (stock) Android Email app, not the Gmail app. The reason being that there is no option to turn off conversation view.

I am trying to follow Google's own advice about Recommended IMAP client settings. I quote:


  If you're not using one of the above listed clients, as a general
  rule, we suggest the following settings:
  
  Sending:
      Do not save sent messages on the server. If your client is sending mail through Gmail's SMTP server, your sent messages will be automatically copied to the [Gmail]/Sent Mail folder.


But I just can't find any setting to turn off the saving of sent messages on the server. Am I blind or does this feature not exist?

[rant on] Seriously, trying to configure Gmail IMAP access with all kinds of different email clients (desktop and mobile) gives me never ending headaches and eats up all my free time. [rant off]
I think there is no need to set those settings in the Email app. You only need to set them in e-mail clients where you are getting duplicate copies of the email, provided those clients have a way of setting those settings. 

If you notice in the image below (from the desktop GMail web app), there is a Sent Mail and an [Imap]/Sent folder. The Sent Mail folder is GMail's, while the [Imap]/Sent folder is generated by a 3rd-party client (like Thunderbird or Kaiten, for example). 



Ideally, a sent mail would be placed under Sent Mail or under [Imap]/Sent. In some cases, it gets copied under both. So now, you have two copies of the sent email. If this is happening, then you need to follow the Recommended IMAP client settings. If not, you're fine.

Related reference:
https://webapps.stackexchange.com/questions/16868/gmail-and-imap-how-do-the-imap-drafts-imap-sent-and-imap-trash-folders