Why don’t the total count on my Inbox and its sub-mailboxes add up?
The counts should not necessarily add up.
An email sent TO two of your email accounts at the same time would be listed in your two sub email accounts.
e.g.
TO: email_account_1@acme.com, email_account_2@acme.com
Subject: test
It would produce those counts:
Inbox (total: 1)
-> email account 1 (total: 1)
-> email account 2 (total: 1)
A conversation can also be in your main Inbox mailbox without any email received in your email accounts. For example, if a colleague receives an email in a personal email account and then invites you to the conversation.
It would produce those counts:
Inbox (total: 1)
-> email account 1 (total: 0)
-> email account 2 (total: 0)