A user with a mailbox hosted on Exchange 2016 (on-premises or in 365) is unable to retrieve messages. You see the following error in the ArchiveOne service trace:
21 14:55:39 OpenMailboxFromAutoDisoveryData OpenMsgStore failed 0x80040110
21 14:55:39 FEE_RemoveProfile called for profile AO_UnifiedMailboxLogon_48016b27
21 14:55:39 CAMComplianceServer::GetMessage failed to open mailbox 0x80040110
The mailbox logon fails with the MAPI error 0x80040110 (MAPI_E_VERSION) as downloadable MAPI is not compatible with Exchange 2016 environments.
You should upgrade to ArchiveOne v7.2 or later as this utilizes Outlook MAPI as opposed to downloadable MAPI, providing support for Exchange 2016 environments.