If any connectors already exist for your organization, you can see them listed here.
Before you set up a new connector, check any connectors that are already listed here for your organization. For example, if you ran the Exchange Hybrid Configuration wizard, connectors that deliver mail between Office 365 and Exchange Server will be set up already and listed here. You do not need to set them up again, but you can edit them here if you need to.
If you don’t plan to use the hybrid configuration wizard, or if you’re running Exchange Server 2007 or earlier, or if you’re running a non-Microsoft SMTP mail server, set up connectors using the wizard.
To start the wizard, click the plus symbol +. On the first screen, choose the options that are depicted in the following screenshot:
Click Next, and follow the instructions in the wizard. Click the Help or Learn More links if you need more information. The wizard will guide you through the setup. At the end, make sure your connector validates. If the connector does not validate, double-click the message displayed to get more information.