Help getting SPF to work

[stan]

I'm trying to get SPF working on a FreeBSD 4.11 machine. I've added the 
sid-milter from ports, and it appears to be working. But I've set up a
test domain with, what I believe to be a correct SPF
record. The domain is i-v-o.net , and here's the yxy record for that
domain:

i-v-o.net       text = "v=spf1 a mx ptr ~all"

But when I send a message from this domain, and the milter checkis
it I get:

Authentication-Results: prod1.ivo.net from=stan at i-v-o.net; sender-id=softfail; spf=neutral

The from on this meeage looks like:

From: stan <stan at i-v-o.net>

Although there is also this from line:

>From stan at prod1.ivo.net  Fri Sep 16 23:41:04 2005

Is this part of the problem? If so, how can I solve this?
This machine will serve as the mailhost for several virtual domains.

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