I installed Lync and configured.
I CAN send outbound email from my 365 account but when the recipient replies to it, the return route is not working.
Same error occurs if just trying to email to my 365 email account.
host
inboundsmtpprofile-250466-mail5.customer.frontbridge.com[157.56.242.236]
said: 550 5.7.1 Unable to relay (in reply to RCPT TO command)