Microsoft Outlook polls your email accounts after certain intervals to see if there are any new emails in your accounts, however if you want to do this manually you can use a shortcut key to quickly poll all your email accounts, which will save you some time and efforts if you decided to do it using a mouse.
Using the F9 key, you can quickly do a send/receive on all your accounts. Outlook also allows users to definite which groups should be included while doing a send/receive all using the F9 key.
To change the settings for this option, use the shortcut key Ctrl + Alt + S, this should popup a new window, where you can change the group settings for send/receive all option.
You can also use the same setting window to control whether emails are automatically fetched and how often they are fetched, if you are using a low bandwidth internet connection, you could save some bandwidth by clicking on the Edit button to edit the email group and change the settings to only download headers instead of full emails.