Opening or deleting emails from WebAccecss does not update a screen information. You need manually to refresh the screen to see changes made.
This has been reported to our development. However, using newer FTF builds of 18.1, for instance the build 132451 or later do seem to resolve this problem.
You might also enable the "EnableTcpSoapSlap" switch in each startup configuration file of POA and then restart it to take effect. Note, pay attention to your firewall settings and that would require to open TCPIP communication on port 8500. Without that switch POA will send UDP based slaps.