diff --git a/app/handler/provider_complaint.py b/app/handler/provider_complaint.py
index 92614809..a0711aa6 100644
--- a/app/handler/provider_complaint.py
+++ b/app/handler/provider_complaint.py
@@ -51,6 +51,11 @@ class ProviderComplaintOrigin(ABC):
     def sanitize_addresses(
         cls, rcpt_header: Optional[str], message: Message
     ) -> Optional[OriginalAddresses]:
+        """
+        If the rcpt_header is not None, use it as the valid rcpt address, otherwise try to extract it from the To header
+        of the original message, since in the original message there can be more than one recipients.
+        There can only be one sender so that one can safely be extracted from the message headers.
+        """
         try:
             if not rcpt_header:
                 rcpt_header = message[headers.TO]
diff --git a/pytest.ini b/pytest.ini
index 3d362baf..c0f5472c 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,5 +1,5 @@
 [pytest]
-addopts =
+xaddopts =
     --cov
     --cov-config coverage.ini
     --cov-report=html:htmlcov