On Friday, 11 July 2008, at 18:29:06 (+0200),
Ralf S. Engelschall wrote:

> Ah, I see: your are sending from a host which has no PTR record in
> the DNS.

No, he's sending from a host with intermittent DNS failures:

mej@quasar ~ >> host 17.148.16.88
88.16.148.17.in-addr.arpa domain name pointer asmtpout013.mac.com.

So clearly there *is* a PTR record...rpm5.org just didn't find it at
the time.  Are you not using a local caching DNS server?

Michael

-- 
Michael Jennings (a.k.a. KainX)  http://www.kainx.org/  <mej@kainx.org>
Linux Server/Cluster Admin, LBL.gov       Author, Eterm (www.eterm.org)
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 "It is possible to commit no mistakes and still lose.  That is not a
  weakness; that is life."       -- Captain Picard, "Peak Performance"