Yes you can! follow this steps :-
1
Launch Outlook, click "File" and choose "Options" from the menu to open the Outlook Options window.
2
Click "Advanced" in the left pane to view the advanced settings and then click the "Send/Receive" button in the Send and Receive section to open the Send/Receive Groups window.
3
Select the "All Accounts" group from the Group Name list and then click the "Edit" button to open the "Send/Receive Settings - All Accounts" window
4
Uncheck the "Send mail items" box in the Account Options section and then click "OK" to stop Outlook from sending emails.
5
Click "Close" and then "OK" to close all windows and return to the main Outlook window.
Hope it works and solves your problem.