diff --git a/Makefile b/Makefile
index 05029946..a64deb56 100644
--- a/Makefile
+++ b/Makefile
@@ -9,6 +9,7 @@ build:
 run:
 	# Copy test files
 	cp test/accounts.cf postfix/
+	cp test/main.cf postfix/
 	cp test/virtual postfix/
 	# Run containers
 	docker run -d --name mail \
@@ -51,6 +52,6 @@ tests:
 
 clean:
 	# Get default files back
-	git checkout postfix/accounts.cf postfix/virtual
+	git checkout postfix/accounts.cf postfix/main.cf postfix/virtual
 	# Remove running test containers
 	docker rm -f mail mail_pop3 mail_smtponly
diff --git a/test/main.cf b/test/main.cf
new file mode 100644
index 00000000..37155392
--- /dev/null
+++ b/test/main.cf
@@ -0,0 +1,2 @@
+max_idle = 600s
+readme_directory = /tmp
diff --git a/test/tests.bats b/test/tests.bats
index be681fb1..89de473e 100644
--- a/test/tests.bats
+++ b/test/tests.bats
@@ -217,6 +217,13 @@
   [ "${lines[1]}" = "otherdomain.tld" ]
 }
 
+@test "checking postfix: main.cf overrides" {
+  run docker exec mail grep -q 'max_idle = 600s' /tmp/postfix/main.cf
+  [ "$status" -eq 0 ]
+  run docker exec mail grep -q 'readme_directory = /tmp' /tmp/postfix/main.cf
+  [ "$status" -eq 0 ]
+}
+
 #
 # spamassassin
 #