https://www.ablebits.com/office-addins-blog/schedule-email-delay-delivery-outlook/#:~:text=Disable%20automatic%20email%20sending%20%2F%20receiving,immediately%20when%20connected%20check%20box.
Disable automatic email sending / receiving
To prevent Outlook from sending and receiving email automatically, this is what you need to do:
- Click File > Options, and then click Advanced in the left pane.
- Scroll down to the Send and Receive section and clear the Send immediately when connected check box.
- In the Send and Receive section, click the Send/Receive… button.
- In the dialog window that appears, clear these boxes:
- Schedule an automatic send/receive every … minutes
- Preform an automatic send/receive when exiting
- Click Close.
- Click OK to close the Outlook Options dialog box.
With these three options disabled, you have full control over sending and receiving your mail. To do this, either press F9 or click the Send/Receive All Folders button on the Send/Receive tab of the Outlook ribbon.
If you might be at times absent-minded or are often distracted by phone calls or your colleagues, you may simply forget to timely receive mail and miss important messages. To prevent this from happening, it would be wise to schedule automatic send/receive with a time interval that works best for your needs.
Note. If you performed the above steps but your Outlook still sends and receives mail automatically, most likely you don't have control over your server. Alas, you will have to live with it.