Send email to post reply to forum article
In SalesForce.Com, there is a great integration of emails and sales-force case comments. There is a common email address to which one need to send email, with a reference (generated once by sales-force.com) to the case, and the email gets attached to the case.
I am sure this can be implemented for symconnect also. There are lot of people who access emails through smart devices, or even prefer to use email-clients as much as possible. So for a particular post, he wants to respond, it should be as easy as sending email to the specific id, with some unique reference to the original post. The reference can be embedded when the notification is generated for subscribed users.