Gmail and Outlook provide their services to check the IP reputation and spam reporting.
Register on Google Postmaster: https://postmaster.google.com
Verify your domain name. It will show the reports about the spam rate and IP reputation over time.
Register on Outlook's Smart Network Data Services: https://sendersupport.olc.protection.outlook.com/snds/index.aspx?wa=wsignin1.0
It allows you to add the specific server IPs you will be sending emails from. It will also send you an email each time someone marks your email as spam. Take appropriate actions to keep maintain the reputation.
Register on DNSWL for blacklist reporting: https://www.dnswl.org/selfservice/