RBL check 18.104.22.168
What is a RBL?
RBL stands for Realtime Blackhole List. An RBL lists IP Addresses that are continually accused of sending out email spam. Spam is generally defined as unsolicited or junk email. Internet Service Providers and other companies use the RBL list to block email from certain IP Addresses or Servers that are known for continually engaging in the practice of sending spam email.
If you are receiving unsolicited emails, you can check to the source to determine if the source of the emails is on the RBL list. More importantly, if email you send from your personal or business email address is not being received by others, we suggest you check to see if your IP is on the list. Occasionally, IP may be listed on the RBL by accident because of a few complaints. In addition, spammers sometimes hijack IPs or servers through viruses to send their spam. So your server or IP could be sending spam without your knowledge which may land it on the RBL list.
So periodically checking your IP Addresses using the RBL Check Tool above is recommended.