ERROR:

You getting emails from Plesk, or getting Following error while pressing “Retrieve Keys” from Plesk >> Server >> License Management

Licensing Server Unreachable: Unable to connect with licensing server.
Please make sure that your network allows communication to ka.swsoft.com:5224.
For more details check system help pages

SOLUTION:

Plesk connects Parallels license server at 5224 port for the license update procedure. Make sure that the outgoing connection to ka.swsoft.com:5224 is not blocked on Plesk server or somewhere in the net. This can be examined with commands:

# nmap -P0 -p5224 ka.swsoft.com

[root@support ~]# nmap -P0 -p5224 ka.swsoft.com

Starting nmap 3.70 ( http://www.insecure.org/nmap/ ) at 2008-11-05 10:00 EST
Interesting ports on ka.parallels.com (64.131.90.38):
PORT     STATE    SERVICE
5224/tcp filtered unknown

Nmap run completed -- 1 IP address (1 host up) scanned in 2.205 seconds

# telnet ka.swsoft.com 5224

[root@support ~]# telnet ka.swsoft.com 5224
Trying 64.131.90.38...
Connected to ka.swsoft.com.
Escape character is '^]'.