If a post is set to Email Reply all messages will be delivered via email.
If a user responds to your post it will go to the email address associated with your doublelist profile.
If you respond to another post you can provide any email in the "Email they can reach you at" text box.
Please note that a response sent through doublelist will not show up in your email sent folder. We use our own mail server to send the first message. Once you have established communication with the user the conversation will proceed through your email directly.
If your responses aren't coming through please open a support ticket.