[stunnel-users] Error resolving '...' (Windows)

On a Windows 2000 machine I always get the following error when I try to start stunnel (4.11): Error resolving 'x.y.z.23': Neither nodename nor servname known (EAI_NONAME) The client should connect to a server using SSL. x.y.z.23 is a static IP address of the client. The client has multiple IP addresses and stunnel should use this one to connect to the server. Contents of stunnel.conf: client=yes [service] local=x.y.z.23 accept=12345 connect=server:12345 Why does stunnel try to "resolve" this IP? Is the configuration correct? Thanks for your help! Oliver