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performance question: OWA VS Outlook/RPC over HTTP VS Standard outlook

twinstead asked

I have a network in Mexico that is on the other end of a sonicwall VPN. Since a T1 was going to be prohibitively expensive, we have a dedicated 4mb DSL connection that holds the VPN. Performance is OK, but there is a certain amount of fluctuation over the course of the day, from acceptable to fairly slow.

We have an exchange 2007 server on this end.  Right now, because of the relatively slow bandwidth, all of the users use OWA to connect from the Mexico plant to the exchange server here. They all have outlook 2003, but it isn't used. I'd like many of them to be able to use Outlook.

My question is what would be the best performance option in that situation? Should I just keep them on OWA, configure outlook to connect to the exchange server up here using RPC over HTTP, or use the regular mapi connection of outlook 2003 in cache mode?
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Top Expert 2010
The nice thing about OWA is all the email is on the Exchange server, but that's also the bad part especially if the connection is slow.  If you decide to go to the Outlook client locally, then be prepared for a time delay while the clients cache their email locally.  I'd recommend RPC over HTTP and configure the Outlook client to keep the users off the VPN.  Once the clients have cached, then there should only be the periodic connection as they check for new mail.  I'm not sure what overhead these "check ins" cost.  Another nice thing about Exchange 2007 OWA is that it is so close to the appearance and features of the Outlook client.

Looking at the pros and cons, I'd keep your users on OWA unless you have some power users who have to ALWAYS have access to email even when the connection is down.

Also, have you looked at the cause of the network slow downs?


I think if I am going to ever make the switch to outlook, this would be the time because they have only been there for 6 months. Every day that goes by there will be more and more email to cache.  I think I'll try the RPC over HTTP on a couple and see how it goes.

As far as the network goes, from what I can tell the entire industrial plant slows down during the afternoon. It appears the Mexcian telecommunications infrastructure can have some issues.

Thanks for your advice!
Top Expert 2010

No Problem.  FYI, one thing I discovered with RPC over HTTP (Outlook Anywhere) for Exchange 2007 was the authentication method.  Previously, we utilized Exchange 2003 and NTLM.  When we switched to Exchange 2007, NTLM would not connect.  I contacted Microsoft and discovered that the ability to utilize NTLM in Exchange 2003 was a bug and they fixed that in 2007.  So, Basic is required and when Outlook comes up and tries to connect via Outlook Anywhere, the user is prompted for their domain username and password.  This shouldn't be a problem with your users as they are already required to do that with OWA, but it is a configuration head's up.

Glad I could help and thanks for the points!