In the past, I didn't realize that many members turn off their email forwarding. I suppose this is to avoid spam or items that they are not interested in. I sent emails from the road a week ahead of time while on a cross country ride and ended up wasting many hours with my requests. There were a lot of 'no responses'. Later I would receive apologies from them not to have gotten back to me in time to be helpful. They only received Warmshowers email requests when they got around to logging into the site.
I believe a great new feature of Warmshowers would be to specifically show when a member has his forwarding turned off. This way one can skip them as potential hosts where there is only a short time to give notice. I can remember thinking to myself a number of times, 'I hope he gets back to me. There are no other members nearby'. And by the time I realized he was not going to respond, I had passed him by.
So my idea is to 'display it' when it is turned off, or possibly try another alternative. Don't allow the member to turn off the email forwarding specifically for requests and personal messages, but allow cutting off other mail from the site. If he doesn't want to be bothered at all, have him use the 'not available' feature.
Presently, there is the feature which displays when a member last logged in and this is very helpful. If a member hasn't logged in for a few months, the assumption can be that he or she has become inactive.
I don't mean to be insensitive, but this might help touring riders all over the world.