diff --git a/src/lib/Conf.pm b/src/lib/Conf.pm
index 4a2a2d5fa..10610fcb8 100644
--- a/src/lib/Conf.pm
+++ b/src/lib/Conf.pm
@@ -8,9 +8,9 @@
 # Copyright (c) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
 # 2006, 2007, 2008, 2009, 2010, 2011 Comite Reseau des Universites
 # Copyright (c) 2011, 2012, 2013, 2014, 2015, 2016, 2017 GIP RENATER
-# Copyright 2017, 2018, 2019, 2020, 2021, 2022 The Sympa Community. See the
-# AUTHORS.md file at the top-level directory of this distribution and at
-# <https://github.com/sympa-community/sympa.git>.
+# Copyright 2017, 2018, 2019, 2020, 2021, 2022, 2024 The Sympa Community.
+# See the AUTHORS.md file at the top-level directory of this distribution
+# and at <https://github.com/sympa-community/sympa.git>.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -1517,49 +1517,43 @@ sub _infer_server_specific_parameter_values {
 
     $param->{'config_hash'}{'robot_name'} = '';
 
-    unless ($param->{'config_hash'}{'dkim_signer_domain'}) {
-        $param->{'config_hash'}{'dkim_signer_domain'} =
-            $param->{'config_hash'}{'domain'};
-    }
+    $param->{'config_hash'}{'dkim_signer_domain'} ||=
+        $param->{'config_hash'}{'domain'};
 
-    my @dmarc = split /[,\s]+/,
+    my @dmarc = grep {length} split /[,\s]+/,
         ($param->{'config_hash'}{'dmarc_protection.mode'} || '');
     if (@dmarc) {
-        $param->{'config_hash'}{'dmarc_protection.mode'} = \@dmarc;
+        $param->{'config_hash'}{'dmarc_protection.mode'} = [@dmarc];
     } else {
         delete $param->{'config_hash'}{'dmarc_protection.mode'};
     }
 
-    ## Set Regexp for accepted list suffixes
-    if (defined($param->{'config_hash'}{'list_check_suffixes'})) {
-        $param->{'config_hash'}{'list_check_regexp'} =
-            $param->{'config_hash'}{'list_check_suffixes'};
-        $param->{'config_hash'}{'list_check_regexp'} =~ s/[,\s]+/\|/g;
-    }
-
-#    my $p = 1;
-#    foreach (split(/,/, $param->{'config_hash'}{'sort'})) {
-#        $param->{'config_hash'}{'poids'}{$_} = $p++;
-#    }
-#    $param->{'config_hash'}{'poids'}{'*'} = $p
-#        if !$param->{'config_hash'}{'poids'}{'*'};
+    # Accepted list suffixes.
+    $param->{'config_hash'}{'list_check_suffixes'} = [
+        grep {length} split /[,\s]+/,
+        ($param->{'config_hash'}{'list_check_suffixes'} // '')
+    ];
 
-    ## Parameters made of comma-separated list
+    # Parameters made of comma-separated list.
+    # Note that whitespace character(s) cannot be a separator, because the
+    # value of remove_outgoing_headers can contain them.
     foreach my $parameter (
         'rfc2369_header_fields', 'anonymous_header_fields',
         'remove_headers',        'remove_outgoing_headers'
     ) {
-        if ($param->{'config_hash'}{$parameter} eq 'none') {
+        if ('none' eq ($param->{'config_hash'}{$parameter} // '')
+            or not length($param->{'config_hash'}{$parameter} // '')) {
             delete $param->{'config_hash'}{$parameter};
         } else {
-            $param->{'config_hash'}{$parameter} =
-                [split(/,/, $param->{'config_hash'}{$parameter})];
+            $param->{'config_hash'}{$parameter} = [
+                grep {length} split /\s*,\s*/,
+                $param->{'config_hash'}{$parameter}
+            ];
         }
     }
 
-    foreach
-        my $action (split /\s*,\s*/, $param->{'config_hash'}{'use_blocklist'})
-    {
+    foreach my $action (split /\s*,\s*/,
+        ($param->{'config_hash'}{'use_blocklist'} // '')) {
         next unless $action =~ /\A[.\w]+\z/;
         # Compat. <= 6.2.38
         $action = {
@@ -1576,20 +1570,6 @@ sub _infer_server_specific_parameter_values {
         $param->{'config_hash'}{'blocklist'}{$action} = 1;
     }
 
-    if ($param->{'config_hash'}{'ldap_export_name'}) {
-        $param->{'config_hash'}{'ldap_export'} = {
-            $param->{'config_hash'}{'ldap_export_name'} => {
-                'host'     => $param->{'config_hash'}{'ldap_export_host'},
-                'suffix'   => $param->{'config_hash'}{'ldap_export_suffix'},
-                'password' => $param->{'config_hash'}{'ldap_export_password'},
-                'DnManager' =>
-                    $param->{'config_hash'}{'ldap_export_dnmanager'},
-                'connection_timeout' =>
-                    $param->{'config_hash'}{'ldap_export_connection_timeout'}
-            }
-        };
-    }
-
     return 1;
 }
 
@@ -1611,7 +1591,8 @@ sub _load_server_specific_secondary_config_files {
         || 'en-US';
 
     ## Load charset.conf file if necessary.
-    if ($param->{'config_hash'}{'legacy_character_support_feature'} eq 'on') {
+    if ('on' eq
+        ($param->{'config_hash'}{'legacy_character_support_feature'} // '')) {
         $param->{'config_hash'}{'locale2charset'} = load_charset();
     } else {
         $param->{'config_hash'}{'locale2charset'} = {};
@@ -1694,8 +1675,10 @@ sub _infer_robot_parameter_values {
         Sympa::Language::canonic_lang($param->{'config_hash'}{'lang'})
         or delete $param->{'config_hash'}{'lang'};
 
-    $param->{'config_hash'}{'dkim_signature_apply_on'} =
-        [split /\s*,\s*/, $param->{'config_hash'}{'dkim_signature_apply_on'}];
+    $param->{'config_hash'}{'dkim_signature_apply_on'} = [
+        grep {length} split /[,\s]+/,
+        ($param->{'config_hash'}{'dkim_signature_apply_on'} // '')
+    ];
 
     _parse_custom_robot_parameters(
         {'config_hash' => $param->{'config_hash'}});
@@ -1764,7 +1747,7 @@ sub _check_cpan_modules_required_by_config {
     my $number_of_missing_modules = 0;
 
     ## Some parameters require CPAN modules
-    if ($param->{'config_hash'}{'dkim_feature'} eq 'on') {
+    if ('on' eq ($param->{'config_hash'}{'dkim_feature'} // '')) {
         eval "require Mail::DKIM";
         if ($EVAL_ERROR) {
             $log->syslog('notice',
diff --git a/src/lib/Sympa/Aliases.pm b/src/lib/Sympa/Aliases.pm
index e769c700c..ba202929a 100644
--- a/src/lib/Sympa/Aliases.pm
+++ b/src/lib/Sympa/Aliases.pm
@@ -4,7 +4,7 @@
 
 # Sympa - SYsteme de Multi-Postage Automatique
 #
-# Copyright 2017, 2018, 2021 The Sympa Community. See the
+# Copyright 2017, 2018, 2021, 2024 The Sympa Community. See the
 # AUTHORS.md file at the top-level directory of this distribution and at
 # <https://github.com/sympa-community/sympa.git>.
 #
@@ -108,15 +108,13 @@ sub check_new_listname {
         return ('user', 'incorrect_listname', {bad_listname => $listname});
     }
 
-    my $regx = Conf::get_robot_conf($robot_id, 'list_check_regexp');
-    if ($regx) {
-        if ($listname =~ /^(\S+)-($regx)$/) {
-            $log->syslog('err',
-                'Incorrect listname %s matches one of service aliases',
-                $listname);
-            return ('user', 'listname_matches_aliases',
-                {new_listname => $listname});
-        }
+    my $sfxs = Conf::get_robot_conf($robot_id, 'list_check_suffixes') // [];
+    if (grep { lc("-$_") eq substr $listname, -length("-$_") } @$sfxs) {
+        $log->syslog('err',
+            'Incorrect listname %s matches one of service aliases',
+            $listname);
+        return ('user', 'listname_matches_aliases',
+            {new_listname => $listname});
     }
 
     # Avoid "sympa", "listmaster", "bounce" and "bounce+XXX".
diff --git a/src/lib/Sympa/List.pm b/src/lib/Sympa/List.pm
index c9928553d..c926ed8ce 100644
--- a/src/lib/Sympa/List.pm
+++ b/src/lib/Sympa/List.pm
@@ -153,16 +153,12 @@ sub new {
     $name =~ tr/A-Z/a-z/;
 
     ## Reject listnames with reserved list suffixes
-    my $regx = Conf::get_robot_conf($robot, 'list_check_regexp');
-    if ($regx) {
-        if ($name =~ /^(\S+)-($regx)$/) {
-            $log->syslog(
-                'err',
-                'Incorrect name: listname "%s" matches one of service aliases',
-                $name
-            ) unless ($options->{'just_try'});
-            return undef;
-        }
+    my $sfxs = Conf::get_robot_conf($robot, 'list_check_suffixes') // [];
+    if (grep { lc("-$_") eq substr $name, -length("-$_") } @$sfxs) {
+        $log->syslog('err',
+            'Incorrect listname %s matches one of service aliases', $name)
+            unless $options->{'just_try'};
+        return undef;
     }
 
     my $status;
diff --git a/src/lib/Sympa/Scenario.pm b/src/lib/Sympa/Scenario.pm
index a85f3375e..180454158 100644
--- a/src/lib/Sympa/Scenario.pm
+++ b/src/lib/Sympa/Scenario.pm
@@ -1029,7 +1029,9 @@ sub do_verify_netmask {
     return 0 unless defined $ENV{'REMOTE_ADDR'};
 
     my @cidr;
-    if ($args[0] eq 'default' or $args[0] eq 'any') {
+    unless (length($args[0] // '')) {
+        ;
+    } elsif ($args[0] eq 'default' or $args[0] eq 'any') {
         # Compatibility with Net::Netmask, adding IPv6 feature.
         @cidr = ('0.0.0.0/0', '::/0');
     } else {
@@ -1048,7 +1050,7 @@ sub do_verify_netmask {
     }
     unless (@cidr) {
         $log->syslog('err', 'Error rule syntax: failed to parse netmask "%s"',
-            $args[0]);
+            $args[0] // '');
         die {};
     }
 
@@ -1084,6 +1086,7 @@ sub do_is_owner {
     my $condition_key = shift;
     my @args          = @_;
 
+    return 0 unless defined $args[0] and defined $args[1];
     return 0 if $args[1] eq 'nobody';
 
     # The list is local or in another local robot
@@ -1156,14 +1159,14 @@ sub do_match {
     my @args          = @_;
 
     # Nothing can match an empty regexp.
-    return 0 unless length $args[1];
+    return 0 unless length($args[1] // '');
 
     # wrap matches with eval{} to avoid crash by malformed regexp.
     my $r = 0;
     if (ref $args[0] eq 'ARRAY') {
         eval {
             foreach my $arg (@{$args[0]}) {
-                if ($arg =~ /$args[1]/i) {
+                if (($arg // '') =~ /$args[1]/i) {
                     $r = 1;
                     last;
                 }
@@ -1171,7 +1174,7 @@ sub do_match {
         };
     } else {
         eval {
-            if ($args[0] =~ /$args[1]/i) {
+            if (($args[0] // '') =~ /$args[1]/i) {
                 $r = 1;
             }
         };