The PST provider in Outlook 2007 supports Fast Shutdown. The Wrapped PST sample is built by wrapping objects from the PST provider. Ergo, if a provider built on the Wrapped PST model does not intercept queries for IID_IMAPIClientShutdown, it supports Fast Shutdown.
In other words, if your Wrapped PST based provider has problems with Fast Shutdown, you need to implement IMAPIClientShutdown and return MAPI_E_NO_SUPPORT from QueryFastShutdown. And if your Wrapped PST base provider is OK with Fast Shutdown, but you need to know when it’s happening, you need to implement IMAPIClientShutdown and wrap the PST’s implementation.
Right now, the Sample Transport Provider, MrXP, and the Sample Address Book Provider, SABP, do not implement the Fast Shutdown client interface at all, so if they are installed, Outlook will not use Fast Shutdown.
"so if they are installed, Outlook will not use Fast Shutdown."
Does that mean that Outlook will not use fast shutdown at all if there is a provider in the profile that does not support fast shutdown so that even providers that do support it will not get notified of the imminent shutdown?
Can a single old provider spoil the whole party?
Yes on all counts. We may tweak this in the next version of Outlook.