diff --git a/doc/getting_started/upgrade.rst b/doc/getting_started/upgrade.rst
index 6b25b6ce9..9c41de0f0 100644
--- a/doc/getting_started/upgrade.rst
+++ b/doc/getting_started/upgrade.rst
@@ -68,8 +68,8 @@ following line to your crontab::
 
   0 * * * * <modoboa_site>/manage.py communicate_with_public_api
 
-Please also note that public API now uses TLS so you must update
-your configuration as follows::
+Please also note that public API now uses TLS so you must update your
+configuration as follows::
 
   MODOBOA_API_URL = 'https://api.modoboa.org/1/'
 
diff --git a/modoboa/admin/postfix_maps.py b/modoboa/admin/postfix_maps.py
index b256bd966..2d13440f4 100644
--- a/modoboa/admin/postfix_maps.py
+++ b/modoboa/admin/postfix_maps.py
@@ -52,17 +52,20 @@ class AliasesMap(object):
     mysql = (
         "SELECT alr.address FROM modoboa_admin_aliasrecipient AS alr "
         "INNER JOIN admin_alias AS al ON alr.alias_id=al.id "
-        "WHERE al.enabled=1 AND al.address='%s' AND al.expire_at>now()"
+        "WHERE al.enabled=1 AND al.address='%s' AND "
+        "(al.expire_at IS NULL OR al.expire_at>now())"
     )
     postgres = (
         "SELECT alr.address FROM modoboa_admin_aliasrecipient AS alr "
         "INNER JOIN admin_alias AS al ON alr.alias_id=al.id "
-        "WHERE al.enabled AND al.address='%s' AND al.expire_at>now()"
+        "WHERE al.enabled AND al.address='%s' AND "
+        "(al.expire_at IS NULL OR al.expire_at>now())"
     )
     sqlite = (
         "SELECT alr.address FROM modoboa_admin_aliasrecipient AS alr "
         "INNER JOIN admin_alias AS al ON alr.alias_id=al.id "
-        "WHERE al.enabled=1 AND al.address='%s' AND al.expire_at>now()"
+        "WHERE al.enabled=1 AND al.address='%s' AND "
+        "(al.expire_at IS NULL OR al.expire_at>now())"
     )