Cyrus POP3 Deadlocks in 2.1.16

Michael Loftis mloftis at
Mon Sep 27 14:59:46 EDT 2004

--On Monday, September 27, 2004 11:24 -0500 Michael Sims 
<michaels at> wrote:

> I hope you don't mind me shooting in the dark here...

Not at all, because I've been shooting in the dark on this one for a while 
now :)

> Remember this thread:

Yes I recall that thread, but no, we don't have anything like that going on 
here.  We also don't have any SYN attack going on.  Cyrus POP3 just goes 
dumb and stops working.  If/when it happens again I'll try to catch the 
netstat output, but as I said, it's Cyrus doing this for some reason.

> Do you think it could be relevant?
> What does the output of "netstat -anp" look like when this is happening?
> How about "lsof -ni TCP:pop3"?
> We had a problem with our main mail server a few days ago with SMTP.
> Clients would connect but never get a banner.  Turns out that we had a
> lot of TCP connections stuck in SYN_RECV, which was again caused by the
> network device mentioned in the above thread.  Do you see anything like
> that in your netstat output?

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