Once you've added accounts to Outlook, you can change how often Outlook checks for new email from each account as well as how often Outlook sends outgoing messages from each account.
Below article will show you how you can perform this automatic task:
1. Select Send/Receive > Send/Receive Groups > Define Send/Receive Groups.
2. Select All Accounts > Edit.
3. Select the account you want to remove and uncheck the Include the selected account in the group option,
then select OK.
4. To manually send email from an account you've removed from automatic send/receive, elect Send/Receive > Send/Receive Groups, and then select the account you want to send and receive manually.