I've tried searching for this, but didn't see anything. If you happen to know a
post that relates, please direct me to it.

We have several lists that are email enabled so we can just dump emails into
them, as opposed to manually creating list items and adding attachments. This
all worked fine until we setup Postini spam filtering. Now I can't say 100%
that Postini is causing the issue, but it would be a BIG coincidence for the 2
events to coincide. Basically what happens now is if I send an email to the
list (i.e. forms@...) I receive the following message back:
Your message did not reach some or all of the intended recipients.