Hi We currently have exchange on premises and exchange online, but we cannot the mail routing correct. we have all our federated servers up and have managed to get lync online, but we cannot get the mail boxes to "talk" to each other. Any help or advice would be greatly appreciated

You've asked us to solve a problem but haven't provided any information. You might want to go through this and see what you might have misconfigured. http://technet.microsoft.com/en-us/library/ee681665.aspxEd Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi Can you post event error or NDR? What is provider of exchange online ? exchange online host or office 365 ? Terence Yu TechNet Community Support