From 0300d38f565b1112aa5b19caa3cf2468822989c0 Mon Sep 17 00:00:00 2001
From: Son NK <nguyenkims@hotmail.com>
Date: Wed, 8 Jan 2020 12:42:25 +0100
Subject: [PATCH] make sure delete_header() delete all headers occurences

---
 app/email_utils.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/app/email_utils.py b/app/email_utils.py
index 895a5614..bb78c740 100644
--- a/app/email_utils.py
+++ b/app/email_utils.py
@@ -208,5 +208,8 @@ def add_or_replace_header(msg: Message, header: str, value: str):
 
 
 def delete_header(msg: Message, header: str):
-    if msg[header]:
-        del msg[header]
+    """a header can appear several times in message."""
+    for h in msg._headers:
+        if h[0].lower() == header.lower():
+            msg._headers.remove(h)
+