NFS/Sendmail issue since upgrading to 4.9-STABLE

[Adam Maloney]

Hi all,

I have 3 servers accepting mail, with sendmail in Queue-only mode dropping
mail into an NFS queue (mounted from a 4th machine.)  All 4 machines
involved are running FreeBSD.

I upgraded the 3 NFS clients from 4.8 to 4.9-STABLE on Monday, and started
seeing this sendmail message:

Nov 26 06:51:29 unix20 sm-mta[48069]: (real-message-id): SYSERR(root):
queueup: cannot create queue file ./qf(real-message-id), euid=0: Resource
temporarily unavailable

The df(message-id) file is created and appears to be complete, however the
qf file is 0 bytes.

This happens sporadically, a few times a day on each machine (together doing
about 150,000 messages/day).

I upgraded the NFS server from 4.8 to 4.9 yesterday, thinking that might
help, but the problem is still there.

Any ideas how to troubleshoot this one?