Outlook cache mode not working

I have Exchange 2010 and Outlook clients. All clients are configured to use Exchange cache mode when Exchange is unavailable. However, when Exchange is unavailable and users compose messages they will be presented with a username password dialog box. Any ideas on how to remedy this?
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This is expected behaviour of Exchange 2010 CAS server. In your case, all they need to do is cancel the authentication prompt. However once the Exchange server is back up, they would need to close and reopen Outlook to regain connectivity.

Exchange 2010 does not operate like it did in 2003.
exhuserAuthor Commented:
That is what we had to do. So what is the purpose of the cached mode? The users are getting confused to say the least...Is there a way around this?
Manpreet SIngh KhatraSolutions Architect, Project LeadCommented:
If its Exchange 2010 SP1 or later outlook will automatically reconnect when the server comes back online :)

What is the version of Outlook ...... hope its updated with latest patches\updates.

- Rancy
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exhuserAuthor Commented:
Exchange 2010 v.14.01
Outlook 2010 SP1
exhuserAuthor Commented:
However, the server is offline, Outlook should work in cached mode without a username/password prompt, correct?
@Rancy, I'm afraid that's information is not correct. The CAS server will give the authentication prompt if rebooted. Users will need to close and reopen Outlook, this is not like it was on Exchange 2003.

For further reading see this thread: http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/086f97fd-ab21-4202-8ae1-0c3caba43a53/, take a look at this comment:

Simon_Wu "Yes, the symptom is by designed and I can reproduce it on my lab machine."

Unless anyone can suggest otherwise?

@OP: Yes
exhuserAuthor Commented:
OK, if the server is offline, what is the source of the dialogue box, the username/password prompt?
The connection to the CAS server is broken, hence the authentication prompt. Nothing wrong with that, just need to educate users.
exhuserAuthor Commented:
Who is doing the authentication if the server is not online?
Outlook design
Svet PaperovIT ManagerCommented:

I have followed this discussion for a while and I somehow agree with @exhuser – Outlook should not ask for credentials in Off-line mode (or when the server is unavailable). I don’t have an experience with Outlook 2010 but Outlook 2007 doesn’t do that:

If the client doesn’t have a network connection, Outlook stays disconnected
If the server is inaccessible for some reason, Outlook tries to connect for a while before disconnects completely
If Outlook is disconnected when the server comes online, yes, it needs to be restarted but if the server comes online while Outlook is trying a connection, it reconnects immediately

Our Exchange 2010 SP2 RU4 is still not in production, so I just tested that. We have all Exchange roles on a single server.

@exhuser, what is you setup (servers, roles)? Does the authentication prompt come when the client is disconnected from the network, or when the server is down?
exhuserAuthor Commented:
The authentication prompt comes when the server is down and users attempt to compose messages
exhuserAuthor Commented:
We have evrything on one server MB Role, Client Access Role, Hub Transport Role...
Svet PaperovIT ManagerCommented:
Does this happen when Outlook is connected locally in the domain (domain member) or when it is connected over Outlook Anywhere?

What does Outlook say in the bottom right corner (its connection status) when this happens?
exhuserAuthor Commented:
This is locally on the domain. I believe it says "Not Connected" but I am not sure
Just to clarify what exactly are you looking to do or achieve with the authentication prompt?

I'm curious to see where this is going, as I believe everything being discussed is based around a designed feature, which from a Google search will indicate that everyone is experiencing the same issue.

If you're expecting the prompt to go away or find a way of suppressing it for the benefit of the users, you're looking for something which either doesn't exist or won't be supported.

All my posts on this question, answer you initial question precisely.
exhuserAuthor Commented:
Is this is a "feature" by design, then what is the purpose of having the "cached" mode?  I was looking if Microsoft addressed this in one of its service packs
Yes it is.

Cached mode allows you to have an offline copy of your emails which are downloaded to the local machine as opposed to online. In cached mode, while the server is offline you can cancel the prompt and still access emails, sort, etc.

Cached mode has been around for a while now. The authentication prompt when the server is offline is due to and a shift to a CAS based role on Exchange 2007, using  CAS as the web front end for connection requests, including Outlook.

For further reading of the roles: http://www.msexchange.org/tutorials/Introduction-Exchange-2007-Server-Roles.html

I agree it is little annoying, compared to how seamless it was in Exchange 2003, but this is just the way it is. I'm sure MS takes feedback from forums, etc and will improve on these annoyances in future releases.
Svet PaperovIT ManagerCommented:
Sorry, I’ve being busy today working for my bosses :-)

I will recommend updating your Exchange 2010 up to SP2 and its latest RU, I think it was RU4.

We are about to go live with our server; I did a lot of testing the last months and in a lab environment before, I’ve never experienced such issue.

I’ve tried to simulate the problem you have but I wasn’t able: neither Outlook 2007 not Outlook 2010 ask for authentication in local connection or over Outlook Anywhere. Even more: if either Outlook 2007 or Outlook 2010 is disconnected when it is on the local network, it comes online when Exchange is up again – no restart is required.

That makes me think that for any reason may be your Outlook tries Outlook Anywhere connection which has not been configured to use the cached credentials. Did you try your Outlook from outside, over Internet? Does it ask for credentials? The default behaviour of Outlook Anywhere with Exchange 2010 is to ask for credentials even on a domain member computer but this can be changed to use the cached credentials so that Outlook works in the same way as it was on the local network.
Svet PaperovIT ManagerCommented:
Here is the setup for Outlook Anywhere, I was talking about:

Enable Outlook Anywhere with client authentication method of NTLM
Edit the Authentication settings of the Rpc virtual directory in IIS:
Enable Basic Authentication
Restart IIS
With this setup, the users of domain-member computers won't be prompted for authentication when they use Outlook Anywhere; all other users will be required to provide username and password before connecting via Outlook Anywhere.

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