Quote - Remember that members also have the option to turn on ebots to get an email when a new sitemail is sent to them:)

I never get ebots for my product sales or forum replies, or for any other reason.  I've always had them checked on.  Don't think that not getting a response to a sitemail equals poor service.
 
All of my product readmes include my email address.

As for an appropriate response time, I've managed to answer the questions I've received from customers the same day.  Just lucky I guess.