2 files changed, 9 insertions, 1 deletions
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index ef25a3175f..d634fd8ff5 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1948,7 +1948,8 @@ saml2_config:
 #             localpart_template: Jinja2 template for the localpart of the MXID.
 #                 If this is not set, the user will be prompted to choose their
 #                 own username (see the documentation for the
-#                 'sso_auth_account_details.html' template).
+#                 'sso_auth_account_details.html' template). This template can
+#                 use the 'localpart_from_email' filter.
 #
 #             confirm_localpart: Whether to prompt the user to validate (or
 #                 change) the generated localpart (see the documentation for the
diff --git a/docs/templates.md b/docs/templates.md
index b251d05cb9..f87692a453 100644
--- a/docs/templates.md
+++ b/docs/templates.md
@@ -36,6 +36,13 @@ Turns a `mxc://` URL for media content into an HTTP(S) one using the homeserver'
 
 Example: `message.sender_avatar_url|mxc_to_http(32,32)`
 
+```python
+localpart_from_email(address: str) -> str
+```
+
+Returns the local part of an email address (e.g. `alice` in `alice@example.com`).
+
+Example: `user.email_address|localpart_from_email`
 
 ## Email templates