Hi everyone,
This issue was resolved in SmarterMail 15.7.6956 which was released on Jan 17, 2019:
Fixed: Web interface does not update for new notifications or incoming mail.
Please note: If a system admin is impersonating the mailbox, new messages will NOT refresh in the list. This is expected behavior and designed to behave this way. However, if a domain admin or end user logs in directly, their mailbox should update as expected.
Andrea Free
SmarterTools Inc.
877-357-6278
www.smartertools.com