Description of problem:
The default /etc/fail2ban/filter.d/postfix-rbl.conf is looking for the wrong regex/code according to what postfix logs. /etc/fail2ban/filter.d/postfix-rbl.conf is looking for "...454 4.7.1...". Enabling "reject_rbl_client" in /etc/postfix/main.cf logs offenders as "...554 5.7.1..." which misses the fail2ban rule.


Version-Release number of selected component (if applicable):
[root@server filter.d]# rpm -q postfix
postfix-2.10.1-6.el7.x86_64
[root@server filter.d]# rpm -q fail2ban
fail2ban-0.9.5-3.el7.noarch

How reproducible:
1) With a default installation of postfix with at least one instance of reject_rbl_client xxx in main.cf (likely in smtpd_recipient_restrictions),
2) And fail2ban/postfix-rbl.conf enabled,
3) fail2ban-regex /var/log/maillog /etc/fail2ban/filter.d/postfix-rbl.conf
All log lines/offenders are missed by the default rule


Steps to Reproduce:
1. install postfix and fail2ban/postfix-rbl with at least one instance of "reject_rbl_client xxx" on incoming mail
2. wait for spammers to send mail from RBL'd ip's
3. fail2ban-regex /var/log/maillog /etc/fail2ban/filter.d/postfix-rbl.conf shows all lines as "missed"

Actual results:
[root@server filter.d]# fail2ban-regex /var/log/maillog /etc/fail2ban/filter.d/postfix-rbl.conf 

Running tests
=============

Use   failregex filter file : postfix-rbl, basedir: /etc/fail2ban
Use         log file : /var/log/maillog
Use         encoding : ANSI_X3.4-1968


Results
=======

Failregex: 0 total

Ignoreregex: 0 total

Date template hits:
|- [# of hits] date format
|  [5768] (?:DAY )?MON Day 24hour:Minute:Second(?:\.Microseconds)?(?: Year)?
`-

Lines: 5768 lines, 0 ignored, 0 matched, 5768 missed
[processed in 0.58 sec]

Missed line(s): too many to print.  Use --print-all-missed to print all 5768 lines


Expected results:
[root@server filter.d]# fail2ban-regex /var/log/maillog /etc/fail2ban/filter.d/postfix-rbl.conf 

Running tests
=============

Use   failregex filter file : postfix-rbl, basedir: /etc/fail2ban
Use         log file : /var/log/maillog
Use         encoding : ANSI_X3.4-1968


Results
=======

Failregex: 2 total
|-  #) [# of hits] regular expression
|   1) [2] ^(?:\[\])?\s*(?:<[^.]+\.[^.]+>\s+)?(?:\S+\s+)?(?:kernel: \[ *\d+\.\d+\]\s+)?(?:@vserver_\S+\s+)?(?:(?:(?:\[\d+\])?:\s+[\[\(]?postfix(-\w+)?/smtpd(?:\(\S+\))?[\]\)]?:?|[\[\(]?postfix(-\w+)?/smtpd(?:\(\S+\))?[\]\)]?:?(?:\[\d+\])?:?)\s+)?(?:\[ID \d+ \S+\]\s+)?NOQUEUE: reject: RCPT from \S+\[<HOST>\]: 554 5\.7\.1 Service unavailable; Client host \[\S+\] blocked using .* from=<\S*> to=<\S+> proto=ESMTP helo=<\S*>$
`-

Ignoreregex: 0 total

Date template hits:
|- [# of hits] date format
|  [5768] (?:DAY )?MON Day 24hour:Minute:Second(?:\.Microseconds)?(?: Year)?
`-

Lines: 5768 lines, 0 ignored, 2 matched, 5766 missed
[processed in 0.51 sec]


Additional info:
[root@server filter.d]# postconf -d | grep maps_rbl_reject_code
maps_rbl_reject_code = 554