The TCP offload of bnx NICs like they are build inside Dell PE 2950 servers isn't working correctly in OpenBSD 4.1 and maybe earlier versions. This results in PF rdr (-> spamd) and modulate state not working.

Even though the TCP offload functionality can be disabled at jumper 21 on the Dell PE2950 serverboard you can also use the following patch between the 4.1-release and -current as of 2007/09/05 (and recompile the kernel) if you do not have direct hardware access.

41_bnx_tcp-offload.patch