I noticed on the Windows DHCP service there's an option to add SMTP servers to the information provided to DHCP clients. I've never heard of this before, but it sounds useful, especially for when our ISP's SMTP server experiences problems. How would I get, e.g., Thunderbird to get its SMTP settings via DHCP?
I don't believe any tools exist to currently do this.
If you where interested in developing software I believe you would have to write a program that interacts with the DHCP client via the DHCP Client API on Windows. Your program would have to request the SMTP settings and then do whatever was necessary to reconfigure your Mail client. Reconfiguring Thunderbird would just require tweaking the right configuration file.
On the Linux side you would need to update your dhclient.conf to request the SMTP settings and then write a hook script that accepts the settings and then uses them to update right configuration files.
Well, any hope of automatic failover is doomed to be dashed. If something major changes in the AD (like trying to fail over a mailserver) you can have significant problems as the DCs try to update all the clients...It doesn't happen in a sane manner, and it's often better to restart services after you make any significant change, than to let them try and propagate it.
Additionally, this sort of thing is windows-centric. It's nice when you have an outlook setup, and all you have to do is log on to the domain, kick up outlook, and tell it to use the exchange server, and you're done, but that sort of integration is really only windows playing with windows.