What are the Advantages of a Shared IP Address vs. a Dedicated IP Address?

An important decision that all growing email marketers must address is deciding when emails should be sent from dedicated vs. shared IP addresses.  A dedicated IP address allows the sender full control of emails sent from their IP address. A shared IP address means other senders mailing campaigns utilize the same IP address. This is extremely important because one of the major factors in determining what emails get blocked or marked as spam by mailbox providers is the reputation of the IP address sending it. Below is a brief list of the major advantages for each.

Dedicated IP Address Advantages:

  • Establish and be accountable for one’s own IP reputation –your emails won’t get grouped with other less diligent senders and therefore ensures better Inbox placement
  • Easier to troubleshoot root cause of deliverability issues - dedicated IP address allows you to measure and interpret IP address reputations in products like Return Path’s Email Intelligence Suite
  • Eligible for Return Path Certification which provides qualified senders an average 27% increase of inbox placement
  • Segmentation on multiple dedicated IP addresses allows senders to segment based on message type, or engagement level, etc.
  • Protect critical mail streams (transactional mail)

Shared IP Address Advantages:

  • Low-volume mailers are able to establish a reputation and history with Mailbox Providers
  • Seasonal mailers do not need to warm up dedicated IP addresses every year
  • Cheap and Inexpensive

As with buying any type of product or service, it comes down to what you need to run your business. Shared IP addresses would probably suit seasonal mailers and low-volume senders the best. 

A dedicated IP address is a common recommendation since it lets you grab the steering wheel and take control of your email deliverability. Tools like Return Path’s Reputation Monitor, Microsoft’s SNDS or AOL’s IP reputation tool measure metrics around spam traps, complaints, unknown users, and can help in assessing the success of the IP overall. However, those numbers and grades do not say anything about the success of your specific email program if you are on a shared IP address. Return Path Certification is another way to empower the deliverability of your email program, and is a benefit not offered to shared IP addresses.

The best advice is to use a dedicated IP address when at all possible. This will allow you to measure and interpret any reputation issues more effectively using Return Path's products and services. Knowing what is going on with the reputation of your IP address is imperative. If you're in a shared space, and dedicated IP addresses aren't an option for you yet, ask your ESP what types of clients are sharing your IP addresses, and what the vetting process is for when new clients and email lists are added.  The other senders from the shared IP will affect your inbox delivery for better or worse, and on a shared IP address you're only as good as the weakest sender.