Our calendar publishing host will work fine for awhile, then lose connection to the poa. The log entry will state "Failed to connect to Post Office (xxx.xxx.xx.xx) for Calendar/Freebusy publishing." Entries in previous logs will show where it's connecting just fine. When this happens, I've tried restarting all the Groupwise modules (poa, mta, webacc, gwia) as well as stopping and starting apache2 and tomcat5. Nothing will bring it back online until I reboot the Linux server. Our setup is:

Server: SLES 10 SP4
Gwinter: 8.0.3-103395
Calhost: 8.0.2-96933
Webaccess: 8.0.3-103395
Client: 8.0.2-92614
Agents: 8.0.3-103395
Gwcheck: 8.0.2-92614
Gwha: 8.0.3-103395