diff --git a/requirements.txt b/requirements.txt
index 2c7c352..6d978e4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,7 +6,7 @@ xmltodict
 geoip2
 dnspython
 imapclient
-mail-parser==3.5.1
+mail-parser
 dateparser
 elasticsearch>=6.3.0,<7.0.0
 elasticsearch-dsl>=6.2.1,<7.0.0
diff --git a/setup.py b/setup.py
index 60573cc..253e362 100644
--- a/setup.py
+++ b/setup.py
@@ -94,7 +94,7 @@ setup(
     # https://packaging.python.org/en/latest/requirements.html
     install_requires=['dnspython', 'publicsuffix', 'xmltodict', 'geoip2',
                       'urllib3', 'requests', 'imapclient',
-                      'mail-parser==3.5.1', 'dateparser',
+                      'mail-parser', 'dateparser',
                       'elasticsearch>=6.3.0,<7.0.0',
                       'elasticsearch-dsl>=6.2.1,<7.0.0', 'kafka-python'
                       ],