[root@prometheus ~]# fail2ban-regex /var/log/maillog /etc/fail2ban/filter.d/postfix-sasl-abuse.conf --print-all-matched

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

Use   failregex filter file : postfix-sasl-abuse, basedir: /etc/fail2ban
Use         log file : /var/log/maillog
Use         encoding : UTF-8


Results
=======

Failregex: 3 total
|-  #) [# of hits] regular expression
|   1) [3] \[<HOST>\], sasl_method=(LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5), sasl_username=[^@]+@\S+$
`-

Ignoreregex: 0 total

Date template hits:
|- [# of hits] date format
|  [118963] (?:DAY )?MON Day 24hour:Minute:Second(?:\.Microseconds)?(?: Year)?
`-

Lines: 118963 lines, 0 ignored, 3 matched, 118960 missed
[processed in 9.65 sec]

|- Matched line(s):
|  Mar 18 21:35:05 prometheus postfix/smtpd[18227]: 3D2A7197F2F46: client=lfbn-1-10554-40.w90-89.abo.wanadoo.fr[90.89.15.40], sasl_method=PLAIN, sasl_username=stephane@de-labrusse.fr
|  Mar 18 22:46:18 prometheus postfix/smtpd[25944]: 9698E197F2F6F: client=lfbn-1-10554-40.w90-89.abo.wanadoo.fr[90.89.15.40], sasl_method=PLAIN, sasl_username=stephane@de-labrusse.fr
|  Mar 19 14:32:29 prometheus postfix/smtpd[25303]: 9D74C197F1E63: client=lfbn-1-10554-40.w90-89.abo.wanadoo.fr[90.89.15.40], sasl_method=PLAIN, sasl_username=stephane@de-labrusse.fr
`-
Missed line(s): too many to print.  Use --print-all-missed to print all 118960 lines