diff --git a/src/mailman/handlers/avoid_duplicates.py b/src/mailman/handlers/avoid_duplicates.py
index e6df7313d..10a8a6bfc 100644
--- a/src/mailman/handlers/avoid_duplicates.py
+++ b/src/mailman/handlers/avoid_duplicates.py
@@ -23,7 +23,9 @@ has already received a copy, we either drop the message, add a duplicate
 warning header, or pass it through, depending on the user's preferences.
 """
 
-from email.utils import getaddresses, formataddr
+import re
+
+from email.utils import formataddr, parseaddr
 from mailman.core.i18n import _
 from mailman.interfaces.handler import IHandler
 from public import public
@@ -56,7 +58,9 @@ class AvoidDuplicates:
         # Figure out the set of explicit recipients.
         cc_addresses = {}
         for header in ('to', 'cc', 'resent-to', 'resent-cc'):
-            addrs = getaddresses(msg.get_all(header, []))
+            addrs = []
+            for addr in msg.get_all(header, [])
+                addrs.append(parseaddr(re.sub('[\r\n]', '', addr)))
             header_addresses = dict((addr, formataddr((name, addr)))
                                     for name, addr in addrs
                                     if addr)

The above patch is invalid. It is missing a colon at the end of

+            for addr in msg.get_all(header, [])