diff --git a/email_handler.py b/email_handler.py
index fae42ca6..10b062f9 100644
--- a/email_handler.py
+++ b/email_handler.py
@@ -258,8 +258,8 @@ def replace_header_when_forward(msg: Message, alias: Alias, header: str):
     Replace CC or To header by Reply emails in forward phase
     """
     new_addrs: [str] = []
-
-    for contact_name, contact_email in getaddresses(msg.get_all(header, [])):
+    headers = msg.get_all(header, [])
+    for contact_name, contact_email in getaddresses(headers):
         # convert back to original then parse again to make sure contact_name is unicode
         addr = formataddr((contact_name, contact_email))
         contact_name, contact = parseaddr_unicode(addr)
@@ -270,10 +270,7 @@ def replace_header_when_forward(msg: Message, alias: Alias, header: str):
             continue
 
         if not is_valid_email(contact_email):
-            LOG.exception(
-                "invalid contact email %s. Skip",
-                contact_email,
-            )
+            LOG.exception("invalid contact email %s. %s. Skip", contact_email, headers)
             continue
 
         contact = Contact.get_by(alias_id=alias.id, website_email=contact_email)