I am seeing a delay when sending email and using SpamAssassin to scan outgoing emails.

Symptoms

I am seeing a delay when sending email and using SpamAssassin to scan outgoing emails. The following error message is logged via the /var/log/maillog file:

Aug 28 16:31:51 vs2 spamd[2746150]: pyzor: check failed: Mail::Pyzor::X::Timeout: Did not receive a response from the pyzor server public.pyzor.org:24441 for 3.5 seconds!

Description 

This issue is caused due to the server being unable to communicate over the port 24411 UDP and TCP which is used by Pyzor. This can be noted with the following script:

# /usr/bin/pyzor  ping
public.pyzor.org:24441    (400, 'Unable to send to public.pyzor.org:24441')

Workaround

Pyzor uses both UDP and TCP port 24441. It looks as though the client communicates with the server via UDP but the server answers back with a TCP connection. You will need to ensure that these connections can be made successfully.

Source: https://cwiki.apache.org/confluence/display/spamassassin/NetTestFirewallIssues