FOO is my client's name - not sure they wanted it to be publicized or not, but imagine FOO was something else.
I got back:
Delivery to the following recipient failed permanently:
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain FOO.com by mail.FOO.com. [184.108.40.206].
The error that the other server returned was:
554 5.7.1 : Client host rejected: Access denied
----- Original message -----
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
That seems to indicate it's dreamhost blocking. It's not happening all the time - it's intermittent right now. Maybe it's gone away now? (fingers crossed)