Thanks for your reply.
The messages originates outside BizTalk from a system, that calls BizTalk using an exposed web service. In BizTalk the orchestration is invoked and in turn invokes a web service with the original message to another system. It is imperative that the BizTalk web service responds to the calling system even if the other system isn't responding – however it would still sometimes be necessary to (after a user has analyzed the instance) resend the failed messages.
I find it a little disturbing if it actually is necessary to make your own code for resending failed messages. BizTalk has logic for resending messages, and I really don't like spending time making something that should already be supported. If this scenario isn't supported by BizTalk, why are the messages marked as resumable? Also it would be preferable to be able to use the management console to resend the messages and not some custom interface (to keep the monitoring and management at one joint place).
Regards, Mads.