warning: problem talking to server private/policyd-spf: Connection timed out

Mar 18 13:19:48 mailserver postfix/smtpd[29311]: warning: problem talking to server private/policyd-spf: Connection timed out
Mar 18 13:19:48 mailserver postfix/smtpd[29311]: NOQUEUE: reject: RCPT from unknown[209.85.220.181]: 451 4.3.5 <email address hidden>: Recipient address rejected: Server configuration problem; from=<email address hidden> to=<email address hidden> proto=ESMTP helo=<mail-vc0-f181.google.com>

Because of my company policy of client, I cannot post their domain, so I change to <email address hidden>

The mailserver has a lot of message about "warning: problem talking to server private/policyd-spf: Connection timed out". The email was delayed. Please help

postfix version: 3.0.0
pypolicyd-spf : 1.3.1
pyspf: 2.0.11
pydns: 2.3.6

I already set "Lookup_time=30 and Void_Limit = 5" in policyd-spf.conf, but it still has problem. Please help
Thank you