Outlook Send/Receive icon missing from Ribbon

We attended a customer’s home to trouble shoot the Send/Receive button missing from one of her Outlook email addresses. Also she noticed that no new emails were appearing in her inbox for a few weeks, despite seeing them in her cell phone email application.

Also there were no emails appearing in the inbox of the affected email address. Suspecting that a Folder rule had accidentally been set up to direct the incoming email to the wrong Folder produced no result.

One email address inbox showed the button as normal, but the other was missing the button. If I manually added the button to missing email address, two buttons appears for both email address inboxes!

Going into the email account settings for both email accounts, I saw that both email addresses were delivering to the same inbox, rather than each email address’ respective inbox.
Changing the incorrect inbox setting to the correct inbox, fixed the problem and her emails appeared in the correct inbox. Not only that but the send/receive button had been restrored on the ribbon.

She didn’t know how the settings were changed, but suspected that her Grandson had a hand in it.