diff --git a/NEWS b/NEWS
index 707c9d30b..e6372e2a8 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,7 @@ Bug fixes
  - [eas] make sure we don't sleep for too long when EAS processes need interruption
  - [eas] fixed recurring events with timezones for EAS (#3822)
  - [eas] improve handling of email folders without a parent
+ - [eas] never send IMIP reply when the "initiator" is Outlook 2013/2016 
  - [core] only consider SMTP addresses for AD's proxyAddresses (#3842)
 
 2.3.16 (2016-09-28)
diff --git a/SoObjects/Appointments/SOGoCalendarComponent.m b/SoObjects/Appointments/SOGoCalendarComponent.m
index 4b57a4e0e..478785925 100644
--- a/SoObjects/Appointments/SOGoCalendarComponent.m
+++ b/SoObjects/Appointments/SOGoCalendarComponent.m
@@ -935,6 +935,14 @@
   NSData *bodyData;
   SOGoDomainDefaults *dd;
 
+  // We never send IMIP reply when the "initiator" is Outlook 2013/2016 over
+  // the EAS protocol. That is because Outlook will always issue a SendMail command
+  // with the meeting's response (ie., IMIP message with METHOD:REPLY) so there's
+  // no need to send it twice. Moreover, Outlook users can also choose to NOT send
+  // the IMIP messsage at all, so SOGo won't send one without user's consent
+  if ([[context objectForKey: @"DeviceType"] isEqualToString: @"WindowsOutlook15"])
+    return;
+
   dd = [from domainDefaults];
   if ([dd appointmentSendEMailNotifications] && [event isStillRelevant])
     {