1 files changed, 4 insertions, 3 deletions

diff --git a/src/mailman/handlers/rfc_2369.py b/src/mailman/handlers/rfc_2369.py
index 8c908128b..8cb586abf 100644
--- a/src/mailman/handlers/rfc_2369.py
+++ b/src/mailman/handlers/rfc_2369.py
@@ -85,9 +85,10 @@ def process(mlist, msg, msgdata):
             for archiver in archiver_set.archivers:
                 if not archiver.is_enabled:
                     continue
-                archiver_url = '<{}>'.format(
-                    archiver.system_archiver.list_url(mlist))
-                headers.append(('List-Archive', archiver_url))
+                archiver_url = archiver.system_archiver.list_url(mlist)
+                if archiver_url is not None:
+                    headers.append(('List-Archive',
+                                    '<{}>'.format(archiver_url)))
                 permalink = archiver.system_archiver.permalink(mlist, msg)
                 if permalink is not None:
                     headers.append(('Archived-At', permalink))