diff --git a/docs/docs/configuration.rst b/docs/docs/configuration.rst
index 6883989..dce076b 100644
--- a/docs/docs/configuration.rst
+++ b/docs/docs/configuration.rst
@@ -49,6 +49,17 @@ Usage:
 
    custom_blocks = "toc,example"
 
+custom_html
+-------------
+
+Use to indent custom HTML tags. For example ``<mjml>`` or ``<simple-greeting>``
+
+Usage:
+
+.. code:: ini
+
+   custom_html = "mjml,simple-greeting"
+
 indent
 ------
 
diff --git a/tests/config_custom_html/html.html b/tests/config_custom_html/html.html
new file mode 100644
index 0000000..a5a1acc
--- /dev/null
+++ b/tests/config_custom_html/html.html
@@ -0,0 +1 @@
+<mjml><mj-body>this is a email text</mj-body></mjml>
diff --git a/tests/test_config.py b/tests/test_config.py
index c9e03aa..d20c430 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -33,6 +33,21 @@ def test_custom_tags(runner: CliRunner) -> None:
     )
     assert result.exit_code == 1
 
+def test_custom_html(runner: CliRunner) -> None:
+    result = runner.invoke(djlint, ["tests/config_custom_html/html.html", "--check"])
+
+    assert (
+        """-<mjml><mj-body>this is a email text</mj-body></mjml>
++<mjml>
++    <mj-body>
++        this is a email text
++    </mj-body>
++</mjml>
+"""
+        in result.output
+    )
+    assert result.exit_code == 1
+
 
 def test_extension(runner: CliRunner) -> None:
     result = runner.invoke(djlint, ["tests/config_extension", "--check"])