PDFs being marked as viruses

[Anna35]

We are sending emails from a few MFCs and postini is rejecting some of
those messages as viruses, but they definitely are not. Headers are
below. How can I fix this?

--- Session Transcript ---
Sat 2009-02-28 14:29:19: Parsing message <xxxxxxxxxxxxxxxxxx
\pd50006175566.msg>
Sat 2009-02-28 14:29:19: * From: *******@smtp.verani.com
Sat 2009-02-28 14:29:19: * To: *******@verani.com
Sat 2009-02-28 14:29:19: * Subject: addendum [2/2]
Sat 2009-02-28 14:29:19: * Message-ID:
<20090228.15...@smtp.verani.com>
Sat 2009-02-28 14:29:19: Attempting SMTP connection to [verani.com]
Sat 2009-02-28 14:29:19: Resolving MX records for [verani.com] (DNS
Server: 192.168.1.220)...
Sat 2009-02-28 14:29:19: * P=010 S=000 D=verani.com TTL=(5) MX=
[verani.com.s7a1.psmtp.com] {64.18.6.14}
Sat 2009-02-28 14:29:19: * P=020 S=001 D=verani.com TTL=(5) MX=
[verani.com.s7a2.psmtp.com]
Sat 2009-02-28 14:29:19: * P=030 S=002 D=verani.com TTL=(5) MX=
[verani.com.s7b1.psmtp.com]
Sat 2009-02-28 14:29:19: * P=040 S=003 D=verani.com TTL=(5) MX=
[verani.com.s7b2.psmtp.com]
Sat 2009-02-28 14:29:19: Attempting SMTP connection to
[64.18.6.14:25]
Sat 2009-02-28 14:29:19: Waiting for socket connection...
Sat 2009-02-28 14:29:19: * Connection established (192.168.1.8:2262 -
> 64.18.6.14:25)
Sat 2009-02-28 14:29:19: Waiting for protocol to start...
Sat 2009-02-28 14:29:20: <-- 220 Postini ESMTP 170 y6_17_2c0 ready.
CA Business and Professions Code Section 17538.45 forbids use of this
system for unsolicited electronic mail advertisements.
Sat 2009-02-28 14:29:20: --> EHLO smtp.verani.com
Sat 2009-02-28 14:29:20: <-- 250-Postini says hello back
Sat 2009-02-28 14:29:20: <-- 250-STARTTLS
Sat 2009-02-28 14:29:20: <-- 250-8BITMIME
Sat 2009-02-28 14:29:20: <-- 250 HELP
Sat 2009-02-28 14:29:20: --> MAIL From:<******@smtp.verani.com>
Sat 2009-02-28 14:29:20: <-- 250 Ok
Sat 2009-02-28 14:29:20: --> RCPT To:<*********@verani.com>
Sat 2009-02-28 14:29:21: <-- 250 Ok
Sat 2009-02-28 14:29:21: --> DATA
Sat 2009-02-28 14:29:21: <-- 354 Feed me
Sat 2009-02-28 14:29:21: Sending <xxxxxxxxxxxxxxxxxx
\pd50006175566.msg> to [64.18.6.14]
Sat 2009-02-28 14:30:22: Transfer Complete
Sat 2009-02-28 14:30:22: <-- 571 Virus detected - psmtp
Sat 2009-02-28 14:30:22: --> QUIT