Office 365 groups are the successor to distribution lists. Any emails that are sent to a group email account, e.g. UKBH-All Personnel - Bar Hill, may appear in your Inbox but also within the Group folder
(This doesn't apply to the old-style distribution lists as emails are sent to the list members and will appear in their Inbox)
You can enable/disable this feature by clicking on the Group mailbox and selecting Group Settings on the ribbon at the top of the screen
If the option for All Email and Events is ticked, you will see the group emails in your Inbox.
If you select the Only Replies to You and Events option, the group emails will not appear in your Inbox, meaning you will have to regularly check the group mailbox.