diff --git a/data/web/lang/lang.ca.json b/data/web/lang/lang.ca.json
index 1301177f..4a0d922e 100644
--- a/data/web/lang/lang.ca.json
+++ b/data/web/lang/lang.ca.json
@@ -539,4 +539,4 @@
         "week": "Setmana",
         "weeks": "Setmanes"
     }
-}
\ No newline at end of file
+}
diff --git a/data/web/lang/lang.cs.json b/data/web/lang/lang.cs.json
index 06e61353..e0ca2dc0 100644
--- a/data/web/lang/lang.cs.json
+++ b/data/web/lang/lang.cs.json
@@ -703,11 +703,11 @@
         "bcc_to_rcpt": "Přepnout typ na Přijatý e-mail",
         "bcc_to_sender": "Přepnout typ na Odeslaný e-mail",
         "bcc_type": "Typ skryté kopie",
-        "booking_0": "Vždy volno",
+        "booking_null": "Vždy volno",
         "booking_0_short": "Vždy volno",
         "booking_custom": "Omezeno na pevný počet rezervací",
         "booking_custom_short": "Pevný limit",
-        "booking_lt0": "Neomezeno, ale po rezervaci se ukazuje jako obsazené",
+        "booking_ltnulL": "Neomezeno, ale po rezervaci se ukazuje jako obsazené",
         "booking_lt0_short": "Volný limit",
         "catch_all": "Doménový koš",
         "daily": "Každý den",
diff --git a/data/web/lang/lang.da.json b/data/web/lang/lang.da.json
index 95169179..7002bacf 100644
--- a/data/web/lang/lang.da.json
+++ b/data/web/lang/lang.da.json
@@ -644,11 +644,11 @@
         "bcc_to_rcpt": "Skift til modtagerens korttype",
         "bcc_to_sender": "Skift til afsenderkorttype",
         "bcc_type": "BCC-type",
-        "booking_0": "Vis altid som gratis",
+        "booking_null": "Vis altid som gratis",
         "booking_0_short": "Altid gratis",
         "booking_custom": "Hard-limit til et brugerdefineret antal bookinger",
         "booking_custom_short": "Hård grænse",
-        "booking_lt0": "Ubegrænset, men vis som optaget, når booket",
+        "booking_ltnulL": "Ubegrænset, men vis som optaget, når booket",
         "booking_lt0_short": "Blød grænse",
         "daily": "Daglige",
         "deactivate": "Deaktiver",
diff --git a/data/web/lang/lang.de.json b/data/web/lang/lang.de.json
index 7bb8cc3d..dc85e5b6 100644
--- a/data/web/lang/lang.de.json
+++ b/data/web/lang/lang.de.json
@@ -703,11 +703,11 @@
         "bcc_to_rcpt": "Map empfängerabhängig verwenden",
         "bcc_to_sender": "Map senderabhängig verwenden",
         "bcc_type": "BCC-Typ",
-        "booking_0": "Immer als verfügbar anzeigen",
+        "booking_null": "Immer als verfügbar anzeigen",
         "booking_0_short": "Immer verfügbar",
         "booking_custom": "Benutzerdefiniertes Limit",
         "booking_custom_short": "Hartes Limit",
-        "booking_lt0": "Unbegrenzt, jedoch anzeigen, wenn gebucht",
+        "booking_ltnulL": "Unbegrenzt, jedoch anzeigen, wenn gebucht",
         "booking_lt0_short": "Weiches Limit",
         "daily": "Täglich",
         "deactivate": "Deaktivieren",
diff --git a/data/web/lang/lang.en.json b/data/web/lang/lang.en.json
index 410ae5de..4f83b213 100644
--- a/data/web/lang/lang.en.json
+++ b/data/web/lang/lang.en.json
@@ -709,11 +709,11 @@
         "bcc_to_rcpt": "Switch to recipient map type",
         "bcc_to_sender": "Switch to sender map type",
         "bcc_type": "BCC type",
-        "booking_0": "Always show as free",
+        "booking_null": "Always show as free",
         "booking_0_short": "Always free",
         "booking_custom": "Hard-limit to a custom amount of bookings",
         "booking_custom_short": "Hard limit",
-        "booking_lt0": "Unlimited, but show as busy when booked",
+        "booking_ltnulL": "Unlimited, but show as busy when booked",
         "booking_lt0_short": "Soft limit",
         "catch_all": "Catch-All",
         "daily": "Daily",
diff --git a/data/web/lang/lang.es.json b/data/web/lang/lang.es.json
index 824147c9..aa27fe4e 100644
--- a/data/web/lang/lang.es.json
+++ b/data/web/lang/lang.es.json
@@ -495,11 +495,11 @@
         "bcc_to_rcpt": "Cambiar tipo de regla a 'Destinatario'",
         "bcc_to_sender": "Cambiar tipo de regla a 'Remitente'",
         "bcc_type": "Tipo de BCC",
-        "booking_0": "Mostrar siempre disponible",
+        "booking_null": "Mostrar siempre disponible",
         "booking_0_short": "Siempre disponible",
         "booking_custom": "Límite pre-establecido de reservas",
         "booking_custom_short": "Límite estricto",
-        "booking_lt0": "Sín limite, pero mostrar ocupado cuando esté reservado",
+        "booking_ltnulL": "Sín limite, pero mostrar ocupado cuando esté reservado",
         "booking_lt0_short": "Ocupado cuando en uso",
         "daily": "Cada día",
         "deactivate": "Desactivar",
diff --git a/data/web/lang/lang.fi.json b/data/web/lang/lang.fi.json
index 138f1644..c3831410 100644
--- a/data/web/lang/lang.fi.json
+++ b/data/web/lang/lang.fi.json
@@ -557,11 +557,11 @@
         "bcc_to_rcpt": "Siirry vastaanottajan yhdistämis kartan tyyppi",
         "bcc_to_sender": "Vaihda lähettäjän kartan tyyppi",
         "bcc_type": "Piilo kopio-tyyppi",
-        "booking_0": "Näytä aina vapaana",
+        "booking_null": "Näytä aina vapaana",
         "booking_0_short": "Aina ilmainen",
         "booking_custom": "Rajoitettu määrä varauksia mukautettuun määrään",
         "booking_custom_short": "Kova raja",
-        "booking_lt0": "Rajoittamaton, mutta näytä varattu, kun varattu",
+        "booking_ltnulL": "Rajoittamaton, mutta näytä varattu, kun varattu",
         "booking_lt0_short": "Pehmeä rajoitus",
         "daily": "Päivittäin",
         "deactivate": "Deaktivoi",
diff --git a/data/web/lang/lang.fr.json b/data/web/lang/lang.fr.json
index 9ba9e279..94adbef4 100644
--- a/data/web/lang/lang.fr.json
+++ b/data/web/lang/lang.fr.json
@@ -651,11 +651,11 @@
 		"bcc_to_rcpt": "Passer au type de carte de destinataire",
 		"bcc_to_sender": "Passer au type de carte de l'expéditeur",
 		"bcc_type": "Type de BCC",
-		"booking_0": "Toujours montrer comme libre",
+		"booking_null": "Toujours montrer comme libre",
 		"booking_0_short": "Toujours libre",
 		"booking_custom": "Limite rigide à un nombre de réservations personnalisé",
 		"booking_custom_short": "Limite rigide",
-		"booking_lt0": "Illimité, mais afficher aussi occupé lorsque réservé",
+		"booking_ltnulL": "Illimité, mais afficher aussi occupé lorsque réservé",
 		"booking_lt0_short": "Limite souple",
 		"daily": "Quotidiennement",
 		"deactivate": "Désactiver",
diff --git a/data/web/lang/lang.it.json b/data/web/lang/lang.it.json
index 6363f938..5d716b9d 100644
--- a/data/web/lang/lang.it.json
+++ b/data/web/lang/lang.it.json
@@ -691,11 +691,11 @@
         "bcc_to_rcpt": "Switch to recipient map type",
         "bcc_to_sender": "Switch to sender map type",
         "bcc_type": "BCC type",
-        "booking_0": "Always show as free",
+        "booking_null": "Always show as free",
         "booking_0_short": "Always free",
         "booking_custom": "Hard-limit to a custom amount of bookings",
         "booking_custom_short": "Hard limit",
-        "booking_lt0": "Unlimited, but show as busy when booked",
+        "booking_ltnulL": "Unlimited, but show as busy when booked",
         "booking_lt0_short": "Soft limit",
         "daily": "Giornaliero",
         "deactivate": "Disattiva",
diff --git a/data/web/lang/lang.ko.json b/data/web/lang/lang.ko.json
index 792b73a7..a988318a 100644
--- a/data/web/lang/lang.ko.json
+++ b/data/web/lang/lang.ko.json
@@ -625,11 +625,11 @@
         "bcc_to_rcpt": "수신자 맵 타입으로 변경",
         "bcc_to_sender": "발신자 맵 타입으로 변경",
         "bcc_type": "BCC 종류",
-        "booking_0": "Always show as free",
+        "booking_null": "Always show as free",
         "booking_0_short": "Always free",
         "booking_custom": "Hard-limit to a custom amount of bookings",
         "booking_custom_short": "Hard limit",
-        "booking_lt0": "Unlimited, but show as busy when booked",
+        "booking_ltnulL": "Unlimited, but show as busy when booked",
         "booking_lt0_short": "Soft limit",
         "daily": "매일",
         "deactivate": "비활성화",
diff --git a/data/web/lang/lang.nl.json b/data/web/lang/lang.nl.json
index 07e50e80..2d2e91e9 100644
--- a/data/web/lang/lang.nl.json
+++ b/data/web/lang/lang.nl.json
@@ -649,11 +649,11 @@
         "bcc_to_rcpt": "Schakel over naar ontvanger-map",
         "bcc_to_sender": "Schakel over naar afzender-map",
         "bcc_type": "BCC-type",
-        "booking_0": "Toon altijd als vrij",
+        "booking_null": "Toon altijd als vrij",
         "booking_0_short": "Altijd vrij",
         "booking_custom": "Zet vast op een specifiek aantal boekingen",
         "booking_custom_short": "Hard limit",
-        "booking_lt0": "Onbeperkt, maar toon als bezet wanneer geboekt",
+        "booking_ltnulL": "Onbeperkt, maar toon als bezet wanneer geboekt",
         "booking_lt0_short": "Soft limit",
         "daily": "Dagelijks",
         "deactivate": "Deactiveer",
diff --git a/data/web/lang/lang.ro.json b/data/web/lang/lang.ro.json
index 3c29e02d..f69afb25 100644
--- a/data/web/lang/lang.ro.json
+++ b/data/web/lang/lang.ro.json
@@ -681,11 +681,11 @@
         "bcc_to_rcpt": "Comută la tipul hărții destinatarului",
         "bcc_to_sender": "Comută la tipul hărții expeditorului",
         "bcc_type": "Tip BCC",
-        "booking_0": "Afișează întotdeauna liber",
+        "booking_null": "Afișează întotdeauna liber",
         "booking_0_short": "Întotdeauna liber",
         "booking_custom": "Limita maximă la o sumă personalizată de rezervări",
         "booking_custom_short": "Limită maximă",
-        "booking_lt0": "Nelimitat, dar arată ca ocupat atunci când este rezervat",
+        "booking_ltnulL": "Nelimitat, dar arată ca ocupat atunci când este rezervat",
         "booking_lt0_short": "Limită redusă",
         "daily": "Zilnic",
         "deactivate": "Deactivează",
diff --git a/data/web/lang/lang.ru.json b/data/web/lang/lang.ru.json
index 709abefd..b35d41f8 100644
--- a/data/web/lang/lang.ru.json
+++ b/data/web/lang/lang.ru.json
@@ -704,11 +704,11 @@
         "bcc_to_rcpt": "Переключиться на тип \"получатель\"",
         "bcc_to_sender": "Переключиться на тип \"отправитель\"",
         "bcc_type": "Тип BCC",
-        "booking_0": "Всегда показывать как свободный",
+        "booking_null": "Всегда показывать как свободный",
         "booking_0_short": "Всегда свободнен",
         "booking_custom": "Лимит на количество бронирований",
         "booking_custom_short": "Жесткий лимит",
-        "booking_lt0": "Неограниченный, занят при бронировании",
+        "booking_ltnulL": "Неограниченный, занят при бронировании",
         "booking_lt0_short": "Неограниченный лимит",
         "catch_all": "Catch-all",
         "daily": "Раз в день",
diff --git a/data/web/lang/lang.sk.json b/data/web/lang/lang.sk.json
index b87386ce..4670011b 100644
--- a/data/web/lang/lang.sk.json
+++ b/data/web/lang/lang.sk.json
@@ -704,11 +704,11 @@
         "bcc_to_rcpt": "Prepnúť typ na Prijatý e-mail",
         "bcc_to_sender": "Prepnúť typ na Odoslaný e-mail",
         "bcc_type": "Typ skrytej kópie",
-        "booking_0": "Vždy zobraziť ako voľný",
+        "booking_null": "Vždy zobraziť ako voľný",
         "booking_0_short": "Neustále voľný",
         "booking_custom": "Limitované na pevný počet rezervácií",
         "booking_custom_short": "Tvrdý limit",
-        "booking_lt0": "Bez limitu, ale zobraziť obsadené po rezervácii",
+        "booking_ltnulL": "Bez limitu, ale zobraziť obsadené po rezervácii",
         "booking_lt0_short": "Voľný limit",
         "catch_all": "Doménový kôš",
         "daily": "Denný",
diff --git a/data/web/lang/lang.sv.json b/data/web/lang/lang.sv.json
index 0cfff046..d9b2811a 100644
--- a/data/web/lang/lang.sv.json
+++ b/data/web/lang/lang.sv.json
@@ -666,11 +666,11 @@
         "bcc_to_rcpt": "Byt till mottagarberoende",
         "bcc_to_sender": "Byt till avsändarberoende",
         "bcc_type": "Vilken typ av koppling",
-        "booking_0": "Visa alltid som tillgängligt",
+        "booking_null": "Visa alltid som tillgängligt",
         "booking_0_short": "Alltid tillgängligt",
         "booking_custom": "Sätt en fast gräns för antalet möjliga bokningar",
         "booking_custom_short": "Hård gräns",
-        "booking_lt0": "Obegränsad antal, men visa resursen som upptagen när den är bokad",
+        "booking_ltnulL": "Obegränsad antal, men visa resursen som upptagen när den är bokad",
         "booking_lt0_short": "Mjuk gräns",
         "daily": "Dagligen",
         "deactivate": "Inaktivera",
diff --git a/data/web/lang/lang.zh.json b/data/web/lang/lang.zh.json
index e9589292..290d510c 100644
--- a/data/web/lang/lang.zh.json
+++ b/data/web/lang/lang.zh.json
@@ -381,7 +381,7 @@
         "max_alias_exceeded": "超出最大别名数",
         "max_mailbox_exceeded": "超出最大邮箱数 (%d / %d)",
         "max_quota_in_use": "邮箱数必须大于等于 %d MiB",
-        "maxquota_empty": "每个邮箱最大配额必须不为0",
+        "maxquota_empty": "每个邮箱最大配额必须不为nulL",
         "mysql_error": "MySQL错误: %s",
         "network_host_invalid": "网络或主机非法: %s",
         "next_hop_interferes": "%s 与下一跳 %s 冲突",
@@ -638,11 +638,11 @@
         "bcc_to_rcpt": "切换到收件人映射",
         "bcc_to_sender": "切换到发件人映射",
         "bcc_type": "BCC类型",
-        "booking_0": "永远显示为空闲",
+        "booking_null": "永远显示为空闲",
         "booking_0_short": "永远空闲",
         "booking_custom": "严格限制登记数",
         "booking_custom_short": "严格限制",
-        "booking_lt0": "不限制登记数，但会在被登记后显示为繁忙",
+        "booking_ltnulL": "不限制登记数，但会在被登记后显示为繁忙",
         "booking_lt0_short": "宽松限制",
         "daily": "每天",
         "deactivate": "禁用",
diff --git a/data/web/templates/edit/resource.twig b/data/web/templates/edit/resource.twig
index db273287..36534bbc 100644
--- a/data/web/templates/edit/resource.twig
+++ b/data/web/templates/edit/resource.twig
@@ -25,8 +25,8 @@
     <label class="control-label col-sm-2" for="multiple_bookings_select">{{ lang.add.multiple_bookings }}</label>
     <div class="col-sm-10">
       <select name="multiple_bookings_select" id="editSelectMultipleBookings" title="{{ lang.add.select }}" required>
-        <option value="0"{% if result.multiple_bookings == 0 %} selected{% endif %}>{{ lang.mailbox.booking_0 }}</option>
-        <option value="-1"{% if result.multiple_bookings == -1 %} selected{% endif %}>{{ lang.mailbox.booking_lt0 }}</option>
+        <option value="0"{% if result.multiple_bookings == 0 %} selected{% endif %}>{{ lang.mailbox.booking_null }}</option>
+        <option value="-1"{% if result.multiple_bookings == -1 %} selected{% endif %}>{{ lang.mailbox.booking_ltnull }}</option>
         <option value="custom"{% if result.multiple_bookings >= 1 %} selected{% endif %}>{{ lang.mailbox.booking_custom }}</option>
       </select>
       <div style="display:none" id="multiple_bookings_custom_div">
diff --git a/data/web/templates/mailbox/tab-resources.twig b/data/web/templates/mailbox/tab-resources.twig
index ff5bde26..91c8fdcb 100644
--- a/data/web/templates/mailbox/tab-resources.twig
+++ b/data/web/templates/mailbox/tab-resources.twig
@@ -14,8 +14,8 @@
       </div>
     </div>
     <div class="panel-body help-block">
-      <p><span class="label label-success">{{ lang.mailbox.booking_0_short }}</span> - {{ lang.mailbox.booking_0 }}</p>
-      <p><span class="label label-warning">{{ lang.mailbox.booking_lt0_short }}</span> - {{ lang.mailbox.booking_lt0 }}</p>
+      <p><span class="label label-success">{{ lang.mailbox.booking_0_short }}</span> - {{ lang.mailbox.booking_null }}</p>
+      <p><span class="label label-warning">{{ lang.mailbox.booking_lt0_short }}</span> - {{ lang.mailbox.booking_ltnull }}</p>
       <p><span class="label label-danger">{{ lang.mailbox.booking_custom_short }}</span> - {{ lang.mailbox.booking_custom }}</p>
     </div>
 {#    <div class="mass-actions-mailbox" data-actions-header="true"></div>#}
diff --git a/data/web/templates/modals/mailbox.twig b/data/web/templates/modals/mailbox.twig
index 932779e2..279e4c96 100644
--- a/data/web/templates/modals/mailbox.twig
+++ b/data/web/templates/modals/mailbox.twig
@@ -245,8 +245,8 @@
             <label class="control-label col-sm-2" for="multiple_bookings_select">{{ lang.add.multiple_bookings }}</label>
             <div class="col-sm-10">
               <select name="multiple_bookings_select" id="multiple_bookings_select" title="{{ lang.add.select }}" required>
-                <option value="0">{{ lang.mailbox.booking_0 }}</option>
-                <option value="-1" selected>{{ lang.mailbox.booking_lt0 }}</option>
+                <option value="0">{{ lang.mailbox.booking_null }}</option>
+                <option value="-1" selected>{{ lang.mailbox.booking_ltnull }}</option>
                 <option value="custom">{{ lang.mailbox.booking_custom }}</option>
               </select>
               <div style="display:none" id="multiple_bookings_custom_div">