The likelihood when you've already exchanged quite a few emails and suddenly all communication ceases is what you've said - they were interested but something c

The likelihood when you've already exchanged quite a few emails and suddenly all communication ceases is what you've said - they were interested but something changed and now they're not. Coming up with an excuse and 'closing down' a conversation with a salesperson so that they don't come back to you has in my experience been... tricky. It usually takes a bit of back and forth even to do that ("yes, I'm really sure I'm not interested, thanks" x3). Because email is very low social pressure, it's probably just people avoiding the awkwardness / time & effort of doing that. If you want feedback on why they're not interested any more, probably the best way is a phone call, or failing that an email which makes the very clear upfront assumption that the sale is not going to happen, and just asking for a quick reason why they changed their mind (just assume they have upfront as well - 90% of the time you'll be right). I think most people would be happy to do this if they are confident the conversation is really going to end there.