I have an app on Heroku, for which I have pointed a Cname record to both the www and naked domain.
However this is creating a problem when people try to reply to our emails from that domain. They are being routed through Heroku somehow - it is only on reply though:
Delivery has failed to these recipients or groups: email@example.com The server has tried to deliver this message, without success, and has stopped trying. The following organization rejected your message: us-east-1-a.route.herokuapp.com. Diagnostic information for administrators: Generating server: sofia.vsl-net.com firstname.lastname@example.org us-east-1-a.route.herokuapp.com #<us-east-1-a.route.herokuapp.com #4.4.7> #SMTP#
In the case above, they were replying to an email sent from email@example.com.
Fasthosts as usual are no help at all, can anyone shed some light on this?
ETA - It only seems to be some people that are having problems replying to us. I can send/receive from another imap account, and also a gmail account.