Kelvin, I think Luke and Ben have made some valid points. Whilst you have put in alot of time and effort to ensure members are kept up to date via the emails, with all due respect, I believe the email system needs to be revised. I am sure there are many here who do not check their email a/c everyday, and when they do, have it half full of forum emails. I am in this boat, and generally, I just delete them all without even reading. I prefer to just log into the forum to see what is going on. Which brings me to my next point, which I believe puts some at a distinct disadvantage, especially when it comes to New Trip Notifications via email.
Am sure some are lucky to work with a computer in their employment that allows them the opportunity to have access to their email a/c most of the time. There are many who do not and as a result they miss out on the opportunity to join a trip. Some have even commented that they often dont receive a email until the next day and more often than not, the trip has already filled.
I am not a IT guru, you are the one..., but maybe it is worth considering setting up the system so only emails are sent to members who have either joined the trip or expressed interest in it. In other words,the only emails members will receive is in relation to the trip they are joining or interested in, nothing else.
Am not sure if this will cause too much extra work for you, but think it is worth considering. At the very least it might make it a level playing field for those who dont have computer access 24/7, plus a possible upside is that all of us will have to log onto the forum for info on up coming trips etc etc, which might result in more activity.
Anyway, just my thoughts.