diff --git a/docs/compose/.env b/docs/compose/.env
index 69c91d82..7f91c270 100644
--- a/docs/compose/.env
+++ b/docs/compose/.env
@@ -102,6 +102,9 @@ COMPRESSION=
 # change compression-level, default: 6 (value: 1-9)
 COMPRESSION_LEVEL=
 
+# IMAP full-text search is enabled by default. Set the following variable to off in order to disable the feature.
+# FULL_TEXT_SEARCH=off
+
 ###################################
 # Web settings
 ###################################
diff --git a/docs/configuration.rst b/docs/configuration.rst
index 292d4303..8382e063 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -83,6 +83,9 @@ later classify incoming mail based on the custom part.
 The ``DMARC_RUA`` and ``DMARC_RUF`` are DMARC protocol specific values. They hold
 the localpart for DMARC rua and ruf email addresses.
 
+Full-text search is enabled for IMAP is enabled by default. This feature can be disabled
+(e.g. for performance reasons) by setting the optional variable ``FULL_TEXT_SEARCH`` to ``off``.
+
 Web settings
 ------------
 
diff --git a/setup/flavors/compose/mailu.env b/setup/flavors/compose/mailu.env
index 78ecce72..8d94820a 100644
--- a/setup/flavors/compose/mailu.env
+++ b/setup/flavors/compose/mailu.env
@@ -91,6 +91,9 @@ COMPRESSION={{ compression }}
 # change compression-level, default: 6 (value: 1-9)
 COMPRESSION_LEVEL={{ compression_level }}
 
+# IMAP full-text search is enabled by default. Set the following variable to off in order to disable the feature.
+# FULL_TEXT_SEARCH=off
+
 ###################################
 # Web settings
 ###################################