In article <CAArzuot9dGV8N0PBY4P2=u=N_a2T36Y1kR6W4VeeYR+jYgS4LQ@mail.gmail.com> you write:

Did your customer set up an MX for their domain pointing to postini and then forward it to you?

obsmtp.com is Postini's outbound servers for customer mail. In my experience, they gush spam, and Postini management has been impressively hostile to the suggestion that a spam filtering company should, you know, filter spam. On my smallish mail server, I direct nearly all of their mail into the spamtrap, picking out only a handful of envelope domains that I've observed sending legit mail. R's, John

On Sun, Jul 22, 2012 at 8:34 PM, Lyle Giese <lyle@lcrcomputer.net> wrote:

...

I run a smaller email filter service for clients and starting Saturday, we are experiencing heavy traffic aimed at one email account. 99% of the traffic is coming from obsmtp.com servers.

In the last 24 hrs, we have been getting over 1,000 attempts per hour to this account with a couple of peaks at 4,000 per hour.

Not sure if they can help but an offlist contact from them would be nice.