Dedicated IP Addresses
The IP address that your emails are sent from is important, due in large part to the fact that your sender reputation is important to your successful email marketing efforts - and the IP address that your emails originate from has a lot to do with your sender reputation. Many Internet Service Providers (ISPs) look at not only the reputation of the domain you send your marketing emails from but also at the reputation of the IP address for those emails. IP addresses can be either dedicated or shared. Let's look at both types.
A dedicated IP address is dedicated solely to you and your company, and the only emails that are sent from this address are yours. Dedicated email addresses make it very easy to track what is sent out, and also gives you the peace of mind that your email sender reputation is completely under your control. You are responsible for the contents of emails that are sent from your dedicated IP address. By following best practices for email marketing and sending emails only to verified opt-in subscribers, having a dedicated IP address allows you to steer clear of activities that might harm your reputation, and therefore, the deliverability of your marketing emails. A negative aspect of dedicated IP addresses is the cost. There is an initial fee for attaining the IP address, and also a monthly fee for maintenance that is charged. These expenses can make your email campaigns less profitable, as added costs lower your return on investment. Dedicated IP addresses may make more sense for larger companies than it does for smaller, independent marketers.
Shared IP addresses are shared with other senders or other companies, and all of the emails sent from the shared IP address will affect the sending reputations of each person using the address. This can be a good or bad concept - depending upon the quality of the email marketers that share the same address. However, one bad apple really can spoil the whole bunch - so if a marketer decides to do something to soil the reputation of the IP address, your reputation will be soiled as well. On the positive side, the expense of obtaining a shared IP address is much less than a dedicated IP, which can save you or your company money in the long run. The real question is whether saving money now is worth the risk later on.