service/email.md

@@ -499,6 +499,12 @@ A limited number of pager playbooks have written, much more needs to
 be done. See the [tests section](#tests) below for ideas on how to debug
 the submission server.
 
+### Blocking a sender
+
+To block a sender from mailing us entirely, you can add their address
+(the header From) to `profile::rspamd::denylist`. This list is defined
+in `puppet-code:data/common/mail.yaml`.
+
 ### Files are present in /var/mail
 
 The `FilesInVarMail` alert looks like this: