This makes several assumptions based soley upon the sample data provided:

Updated: Simplified 1 regex and improved another.

#! perl -slw
use strict;

my %log;

while( <DATA> ) {
    my( $src, $mode, $rest ) =  m'
        ( ^ \S+ ) \s+ - \s+
        ( [^\[:]+ ) (?: \[ \d+ \] )? : \s*
        ( .+ $  )
    'x;

##    $rest =~ s[ (?: \S+ \. ){1,4} \S+ ][****]gx;
    $rest =~ s[ (?: [\w-]+ \. ){1,4} [\w-]+ ][****]gx;

##    $rest =~ s[ [a-z] (?= [^:]* [A-Z] [^:\s]+ \d ) [^:\s]+
    $rest =~ s[ [a-z] \w+ \d : ][****]gx;

    ++$log{ $src }{ $mode }{$rest};
}

for my $src ( sort keys %log ) {
    print $src;
    for my $mode ( sort keys %{ $log{ $src } } ) {
        print "    $mode";
        print "        ($log{ $src}{ $mode }{ $_ }) $_"
            for sort keys %{ $log{ $src}{ $mode } };
    }
}

__DATA__
your sample data
[download]

Produces (after update):

C:\test>junk5
infocache02
    ldap_cachemgr
        (1) Error: Unable to refresh from profile:tls_automount_profil
+e. (error=1)
        (1) libsldap: Status: 91  Mesg: openConnection: simple bind fa
+iled - Can't connect to the LDAP server
    sendmail
        (3) **** Losing ./**** savemail panic
        (2) **** SYSERR(root): savemail: cannot save rejected email an
+ywhere
mail2-in
    postfix/smtpd
        (2) warning: ****: address not listed for ****
        (4) warning: ****: hostname **** verification failed: hostname
+ nor servname provided, or not known
mail2-out
    ntpd
        (5) sendto(****): Bad file descriptor
    postfix/smtp
        (1) warning: malformed domain name in resource data of MX reco
+rd for ****:
        (1) warning: numeric domain name in resource data of MX record
+ for ****: ****
        (1) warning: valid_hostname: empty hostname
[download]