You are not blacklisted and do have a reverse DNS entry...
Code:
$ blcheck 78.90.73.87
IP 78.90.73.87 NAME unix-heaven.org.
2008-09-28_22:47:58_UTC 87.73.90.78.cbl.abuseat.org. ---
2008-09-28_22:47:58_UTC 87.73.90.78.dnsbl.sorbs.net. ---
2008-09-28_22:47:58_UTC 87.73.90.78.bl.spamcop.net. ---
2008-09-28_22:47:58_UTC 87.73.90.78.zen.spamhaus.org. ---
2008-09-28_22:47:58_UTC 87.73.90.78.combined.njabl.org. ---
So that is not the cause.
It is very likely that FreeBSD.org rejects the first delivery attempt in order to prevent spam. A cracked Windows box sending out spam will not retry delivery, while a real MTA will.
If you followed the Lifewithqmail install you can do
This will flush the queue and is equivalent to
Code:
# /var/qmail/bin/qmail-tcpok
# svc -a /service/qmail-send
IIRC a code 450 means a temporary failure. That is why qmail just deferred delivery and did not give up completely