read -1 errno 35 Resource temporarily unavailable

[Catherine Liao]

Greetings,

I have encountered a problem on my FreeBSD that I cannot seem to 
resolve. The problem started with my install of postfix/sendmail 
reporting "postfix/sendmail[56108]: fatal: <username>(1001): error 
writing queue file: Broken pipe". Through ktrace, I was able to 
identify the an EAGAIN error: read -1 errno 35 Resource temporarily 
unavailable. The folks on the postfix suggested that I should do a 
kernel upgrade, which I was able to complete (5.2 -> 5.4). However, 
the EAGAIN problem with postfix/sendmail still hasn't gone away. 
Further more, mutt is now having troubles. When opening mutt, it 
hangs on opening the user's mailbox under /var/mail/. ktrace shows: 
read -1 errno 35 Resource temporarily unavailable.

I'm not sure what I should do next. Can you provide me with advise / 
pointers on how to go about to do further troubleshooting or how to 
resolve it?

Thanks in advance,

Catherine