What is an IP address? An internet protocol address (IP address) is a numerical label assigned to all of your internet activity. Your IP address is used to communicate your device, location, and connection to the network. Inbox service providers (ISP) such as Gmail, Yahoo, and AOL use your IP address (along with your domain, authentication values, content) and to identify and track the sender of an email. The ISP evaluates the email quality from each sender and assigns the IP and Sender a reputation score. If an IP address is sending spam, phish, or unwanted mail, the ISP will give a low reputation score–which will result in more of your email landing in the spam folder. Your sending reputation is one factor that determines whether an ISP will deliver the message to the inbox or not. A sending reputation is impacted by a variety of factors, some of which can be controlled by the sender. The IP address is a factor that senders can choose to control or not. IP Pool vs. Dedicated IP Senders have two options when using an ESP: an IP pool or a dedicated IP address. When using a shared IP pool, the IPs you use will be shared between other senders and managed by the ESP. Shared IPs are cheaper, but can cost your business in the long term. The other option is to purchase a dedicated IP address. Below we provide more information to help decide which option is best for your business. IP Pool An IP pool is a group of IP addresses that are managed by the ESP. IP pools are available at a lower price since multiple customers are sending email through the same network connection. This connection is great for customers that are not sending a high volume of email. Since the IP Pool is a shared connection, the reputation of the IP address is affected by all of the senders. If one customer sends PHISH or spam, it will affect the reputation and deliverability for the other customers on that IP address. Dedicated IP A dedicated IP address is a private network connection, only used by your business to send email.Your business is in control of warming up the IP address, as well as building and maintaining the IP reputation. Owning the IP and the warm-up, results in a reputation with ISPs that is based only on your email program. If you have built a positive reputation with ISPs, your email deliverability will improve. Benefits of a dedicated IP address A dedicated IP address allows you to connect your sending domain with your new outbound IP address. This is accessible at no additional cost and can be refined by finishing a reverse domain name system (rDNS) setup for your dedicated IP. Having your domain appear in the rDNS gives you better “domain alignment” throughout your message, which means the ISP will see the same domain appear throughout your message from the from address all the way to the domain associated with the IP address. This helps the ISP more accurately judge the results of your business’ results when assigning your sending reputation values and is a best practice they want to see from senders. Along with improving trust between your business and the ISP, a dedicated IP address gives you more accurate information about your sending and results. If your dedicated IP address arrives on a blacklist or hits a lot of spam traps, you'll realize that it's no one else's fault aside from your own. If you are on a blacklist, you can try to figure out what caused the spam trap hits and make appropriate adjustments. When using an IP that is a part of a shared pool, it can be very difficult to accurately identify the source of delivery problems. IP addresses have a large impact on your deliverability and the overall health of your email program. Whether you decide to purchase an IP, or use an IP pool, we recommend you research your IP history and follow email best practices for IP warm up and sending. IP’s are not the only way ISP’s judge your mail. The domain you use is also tracked. Look for a future blog about your domain reputation.