To fix the issue of delayed or slow email delivery in Outlook, there are several steps and best pratices to follow that could help improve delivery:

1. Check your email settings and make sure they are correct for your configuration.


2. Make sure all email messages have a valid Internet-based recipient.


3. Re-launch Outlook in safe mode to clear cached files or disabled add-ins.


4. Disable any third-party applications potentially causing limited or no communication.


5. Check if the email account is set up to delete messages from the server after a certain amount of time.


6. Check if there are any high-volume messages being sent from other individuals.


7. Check if messages are marked as spam or blocked by your spam prevention tool.