The goal here is to improve your service and thus reputation so you have think as the customer.
As a customer how does it help me to use a forum where no one else can participate [no crowdsourcing of input] that I have to actively check, return to, maybe even sign up for?
As a customer why would I be concerned about the difficulties you may have in following an email chain?
If you want a forum for support it should be to encourage your customer base to interact with each other and with you. To communally work through issues, raise up suggestions, pass along tips & tricks. There's lots of value in that but even still it has to be an option... most people want to connect directly, to get personal help with as few steps or barriers as needed.