Private message issue.   

Just got a strange scenario reported by my client yesterday.

Consider following situation:

- UserA has a mailbox in RG-A running Exchange Server 2000
- UserB has a mailbox in RG-B running Exchange Server 2003, this user is 
also configured with forwarding mails to gmail.com in AD user's property. 
(create a contact using UserB@gmail.com as smtp address.)
- There are 2 Exchange Server 2007 CAS installed with NLB configured.
- In Exhchange 2003 Routing Group's view, RGCs are configured like this.

    RG-A <> Ex07 <> RG-B

UserA and UserB can send/reply/forward mails with each other alright. The 
forwarding address at gmail.com can receive mails too, but User-A gets NDR 
when sending private mails. NDR are as follow:

Unable to deliver the message because the originator prohibited redirection 
to an alternate recipient or the message was encrypted
<server.domain.local #5.7.300 smtp;550 5.7.300 RESOLVER.FWD.Blocked; the 
sender prohibited alt recipient redirection on this message>

UserA gets NDR, UserB does not receives the message, UserB's gmail account 
receives the private message.

I had tried to switch the mailflow by connecting RG-A and RG-B directly, 
there's no problem.

Later, I switch back to the model that CAS is in between them and done some 
testing:

- In UserA's outlook, I configured outlook to use "private" sensitivity as 
default and send a private mail to UserB, it's received on both UserB's 
mailbox and UserB's gmail account.

- In UserA's outlook, with "Private" sensitivity set as default. I created a 
mail, changing that mail's sensitivity to "Normal" and press "OK". I then go 
to the same place change sensitivity back to "Private" then send this mail to 
UserB. UserA gets NDR, UserB does not get this mail, UsersB's gmail account 
get this mail.

- I tried to send private mail using OWA, no problem at all.

- Outlook used are 2003 and 2007. Outlook 2003 are with SP2. Both English 
and Traditional Chinese version are tested, same result. I don't have Outlook 
2000 and XP at hand so didn't test with it.

   I think may be it's the mapi issue, but it does not explain why I get no 
NDR when connecting 2000/2003 RG directly and sending it using Outlook.

   RG-A and RG-B has their own SMTP Connector when sending internet mails. 
It's confirmed that private mails received by UserB's gmail account are from 
servers in RG-B by looking into mail header.

  I had configure RGC to use both CAS servers as bridgehead. From 1 server I 
get NDRs in English and another server in T-Chinses. Both server's regional 
setting are the same.

  I had also turn all the loggin level regarding MSExchange Transport to 
"expert" but no luck.

  More information can be provided upon request, thank you.

Kevin Lo

date: Tue, 13 May 2008 12:20:02 -0700   author:   Kevin Lo Kevin