I'm still finding some issues with the interface regarding this. For instance, sometimes I accidentally reply to a new thread that comes into my email client from an address that's not registered in Helpmonks. When I make this mistake, Helpmonks then changes the thread's customer email to my other (non-registered) email address, so that when I go into the Helpmonks app and try to reply back to the customer, it now only sends the reply to my other email address. There's no way to override this and reset the "To" email to the original customer. So the workaround is to create a new message with a new thread and then copy the original message and copy the subject and past into the new message which I can then send out to the original customer.
Overall, it's a big hassle. If only we could simply have the ability to change the "To" email field in the web app, we could avoid this issue. Also, it might help if our customer prefers to receive an email at a different address, we'd have the power to change their address in the thread if we needed to.
Let me know if you'd prefer me to create this as another feature request.
Thanks and I appreciate the hard work your team is providing!