Create a connector from on-premises email server to Office 365 (It will be added automatically if you were using Full Hybrid configuration)
- Logon office 365 portal with administrator account, open Exchange Admin Center.
- Select mail flow and click connectors.
3. Click + to start the wizard.
4. On the Select your mail flow scenario page, select Your Organization’s email server at From: and select office 365 at To: , click Next.
5. On New connector page, enter the name for your connector, click Next.
6. On the How should Office 365 identify email from your email server? page, select By verifying that the subject name on the certificate that the sending server uses to authenticate with Office 365 matches this domain name (recommended), enter your external domain name, click Next.
7. Review the settings and click Save.
Hope you enjoy this post.