A dynamic IP address is assigned to a device on a network, such as a personal computer or phone, and may change every time a device connects to the Internet. It is most often used for home and some business users. A dynamic IP address provides flexibility to Internet Service Providers (ISPs), allowing them to balance resources by disconnecting devices not using the network.
Because dynamic IP addresses change frequently, they are used by spammers to conceal their identity to send spam, viruses and phishing messages. Most mailbox providers automatically block bulk marketing and transactional email coming from a dynamic IP address because they are known sources of spam. A dynamic IP address makes it difficult to consistently and accurately identify a sender’s identity and determine if that sender and the email they are sending are trustworthy.
