Quick answer: Run your address through Blacklist Check to see whether reputation lists currently flag it, then review the listed reason before taking action.
Common reasons an IP gets listed
Outgoing spam, a compromised device on the network, malware-related traffic, or simply inheriting a previously-flagged address from a shared or dynamic pool can all trigger a listing.
What to do if you are listed
Scan for compromised devices, check mail server logs for unusual sending activity, and confirm the issue is resolved before requesting delisting from the reporting service.
Read IP Reputation and Blacklists for the full explanation of how these lists work and why a listing is a signal, not a verdict.
Want to see this in practice? Check your own connection's IP, location and ISP.
Check my IP address