Unable to create PIPE

[Ricardo Albano]

Hello, I'm running qmail with a big concurrency remote (more than 500) and I
get errors like this :

Oct 25 12:30:02 smtp1 qmail: 972487802.399537 delivery 8490: deferral:
qmail-spawn_unable_to_create_pipe._(#4.3.0)/

I think is an os limit, but I don't know where to start.
Any know how to solve this ?

OS : Red Hat 6.2 + qmail-1.03 with qmail big concurrency patch.

Bye
RDA.-