For privacy reasons, I use the JAP and Tor anonymizing proxies for all web access. With JAP, where you select a specific mix, Spamgourmet has no issues. However with Tor, the mix of servers that traffic gets routed through does change regularly, resulting in Spamgourmet seeing accesses from a different IP address.
This causes Spamgourmet to lose session details (it returns the message "There was a problem with your login. Please log in again."). While it is sometimes possible to get as far as the "Send a message" screen, it is more usual to end up having to log in repeatedly.
Switching back to JAP avoids this problem but JAP's performance is dire at the moment (due to a server failure at Dresden). Couldn't Spamgourmet just rely on cookies?