Network & Connectivity
IP Blacklisted
When an IP address appears on a blacklist (also called blocklist or DNSBL), email servers and security services may block traffic from that IP. Blacklisting typically occurs due to spam activity, compromised servers, open relays, or shared hosting with abusive neighbors.
Symptoms
- Emails from your server being rejected by recipients
- Bounce messages mentioning RBL or blacklist
- Connections refused by remote mail servers
- Website traffic blocked by security services
Common Causes
- Server sending spam (compromised account or open relay)
- Shared hosting IP used by spammers
- Previous owner of the IP had bad reputation
- Sudden spike in outbound email volume
Step-by-Step Troubleshooting
- 1
Check IP blacklist status
Scan your IP against major blacklist databases to identify where it's listed.
Use IP Blacklist Check → - 2
Analyze IP reputation
Get detailed threat intelligence and reputation data for your IP.
Use IP Analysis → - 3
Verify reverse DNS
Ensure proper PTR record is set for your IP, which is required by many mail servers.
Use Reverse DNS → - 4
Request delisting
Once the issue is resolved, submit delisting requests to each blacklist provider.
Recommended Diagnostic Tools
Monitor IP Reputation
Get instant alerts if your IP is added to any blacklist.