Office 365 received the message that you specified. Unfortunately, we haven't been able to deliver it to the recipient ({0}) ...

Office 365 received the message that you specified. Unfortunately, we haven't been able to deliver it to the recipient ({0}) yet. We can't deliver the message because Office 365 can't connect to the recipient email server. Either the remote server is not up or the remote email server's firewall is blocking Office 365 from sending messages.