Question : Problem: Bandwidth Requirements for Exchange 2003 / Outlook 2003 over VPN...

I have a company that is attempting to connect a laptop to their Domain / Exchange 2003 server via a simple IPSEC PPTP VPN.  The VPN establishes connectivity with no issue and they can ping all they want to the systems back at HQ (ping latency ~60 - 120 ms).  OWA without the VPN works like  charm; no perceptible latency at all from the user's perspective.

Here are the problems:
1.  Outlook 2003 (not caching) opens initially without issue but immediately begins attempting to communicate with the Exchange 2003 server and seems unable to connect.
2.  Attempting to browse the network / shares is either rediculously slow or results in timeouts after very long delays.  

Here are the specs...
1.  Exchange and File Server:  MS Small Business Server 2003
2.  Exchange Client:  Outlook 2003 (non-caching mode)
2.  Remote Bandwidth:  Residential DSL broadband
3.  HQ Bandwidth:  Commercial DSL with speeds listed as 1.5mb to 6.0 mb down and 384mb up.
4.  Remote VPN client:  Standard VPN connection client in Windows XP (fully patched and service packed)
5.  HQ VPN Hardware:  Fortinet FortiGate 100 VPN / Firewall

I am running relatively the same configuration elsewhere (Exchange 2003 / Outlook XP) with the same VPN configuration and the only difference is that the HQ bandwidth is a full T1 rather than a DSL connection.

I downloaded the bandwidth report on Exchange 2003 and Outlook from Microsoft and read through it but it mostly talks about RPC over HTTP which doesn't solve my network browsing issue and if Bandwidth truly is the problem here, wouldn't solve the problem anyway.

Is the HQ DSL connection the issue here?  Or is software more likely the issue?

Bonus points for thorough well thought out responses :)

Answer : Problem: Bandwidth Requirements for Exchange 2003 / Outlook 2003 over VPN...

This sounds like a name resolution problem - can you successfully nslookup the mail server from the PPTP client ?

Alternatively, I would suggest LMHOSTS, but this is only valid for NT/2000, and not SBS 2003 (unless you have backward compatability installed)?

http://support.microsoft.com/kb/150800/EN-US/

Also verify MTU:

http://www.dslreports.com/faq/695