I'm having a strange issue with some users that sometimes receive a mail message in inbox from outside senders

that displays the 'sent by' as effective sender user@outsidedomain.com and the principal (sender) as the internal user.

I don't know how to reproduce this issue but happens to various users that use traveler client on android or active sync in iphone,

could be the traveler server (9.0.1 with last fix) do that thing ?

Main server: Domino 901 lastfix as 15/12 on windows

Traveler server: Domino 901 lastfix on windows

That issue *apparently* happens when i receive a message that have responses and first read it with traveler on android with certain senders, below there's an example message:

Received:  from relay.mydomain.com ([127.0.0.1])          by mail.mydomain.com (IBM Domino Release 9.0.1 HF32)          with ESMTP id 2013121318563518-722 ;          Fri, 13 Dec 2013 18:56:35 +0100
Received:  from mail2.remotedomain.com (relay.mydomain.com [127.0.0.1])    by relay.mydomain.com (Postfix) with ESMTP id 9297413D8B    for <myuser@mydomain.com>; Fri, 13 Dec 2013 18:56:34 +0100 (CET)
Received:  from mail2.remotedomain.com ([00.00.00.00] helo=mail2.remotedomain.com) by    relay.mydomain.com with SMTP (2.3.3); 13 Dec 2013 18:56:34 +0100
Received:  from remoteserver ([0.0.0.0]) by remoteserver ([0.0.0.0]) with mapi id 14.03.0123.003; Fri, 13 Dec 2013 18:56:34 +0100
From:  remote user <remote.user@remotedomain.com>
SendTo:  "myuser@mydomain.com" <myuser@mydomain.com>
CopyTo:  Support <support@remotedomain.com>
Subject:  R: Testt
Thread_Topic:  Test
Thread_Index:  AQHO+CE0tIcf2A3xfUi2ZxKwtiqXzJpSZcoA
Disposition_Notification_To:  remote user <remote.user@remotedomain.com>
Return_Receipt_To:  <remote.user@remotedomain.com>
PostedDate:  13/12/2013 18:56:35
$MessageID:  <C613D29120C72C478A65E9F76133C6B40CFF2BA2@remoteserver>
References:  <OF91CD1D63.5AF86C6C-ONC1257C40.005AD3B2-C1257C40.005B097D@mydomain.com>
In_Reply_To:  <OF91CD1D63.5AF86C6C-ONC1257C40.005AD3B2-C1257C40.005B097D@mydomain.com>
Accept_Language:  it-IT, en-US
X_MS_Has_Attach:  
X_MS_TNEF_Correlator:  
X_Originating_IP:  [0.0.0.0]
MIME_Version:  1.0
X_Assp_ID:  relay.mydomain.com m1-57394-02149
X_Assp_Session:  FA7E234 (mail 1)
X_Assp_Version:  2.3.3(13276) on relay.mydomain.com
X_Assp_Delay:  not delayed (whitelisted); 13 Dec 2013 18:56:34 +0100
X_Assp_Whitelisted:  Yes (whitelistdb)
ReturnReceipt:  0
$INetOrig:  A117B7BFBB87F6F4EEE2083171EDFC5C
$Created:  13/12/2013 18:56:33
TNEFEvaluated:  1
SMTPOriginator:  remote.user@remotedomain.com
$Orig:  A6FC7D9B654534D5C1257C400062907E
Categories:  
$Revisions:  13/12/2013 18:56:35
RouteServers:  Dominoserver/O=Mydomain/C=COM
RouteTimes:  13/12/2013 18:56:35-13/12/2013 18:56:35
DeliveredDate:  13/12/2013 18:56:35
$TUA:  91CD1D635AF86C6CC1257C40005AD3B2
Principal:  CN=Myuser/O=Mydomain/C=COM  << this is the strange thing
ExcludeFromView:  D
$UpdatedBy:  CN=Travelerserver/O=Mydomain/C=COM
$MIMETrack:  Itemize by SMTP Server on Dominoserver/O=Mydomain/C=COM(Release 9.0.1 HF32|November 25, 2013) at 13/12/2013 18:56:35,MIME-CD by Notes Client on Dominoserver/O=Mydomain/C=COM(Release 9.0.1|October 14, 2013) at 15/12/2013 21:54:19,MIME-CD complete at 15/12/2013 21:54:20

Body following...

Any ideas ?

I may try to reproduce the problem with the same sender tomorrow.

Thanks

MM