What is an IP address? 

• IPv4: 192.168.1.1
• IPv6: 2001:0db8:85a3::8a2e:0370:7334

What are shared and dedicated IPs? 

Shared IP Address 

Dedicated IP Address 

What are the advantages and disadvantages of shared IP?

Advantages 

• No warm-up required. A shared IP pool maintained by a reputable ESP already has an established sending history. New senders can begin delivering at volume immediately without a ramp-up period.
• Lower cost. Infrastructure costs are distributed across many senders. This makes shared IPs the more economical option, particularly for small and mid-size businesses.
• Pooled reputation benefit. On a well-managed shared pool, low-volume senders benefit from the positive reputation built collectively by other responsible senders on the same IP.
• Suitable for irregular sending patterns. Senders with low or inconsistent volumes do not risk IP dormancy issues, which can negatively affect a dedicated IP's reputation during quiet periods.

Disadvantages 

• Shared reputation risk. If another sender in the same IP pool sends spam or generates excessive complaints, all senders on that IP can be affected. Your deliverability can degrade due to factors entirely outside your control.
• Limited control and visibility. You cannot monitor or influence the sending behavior of other senders on the pool. Reputation management is largely delegated to your ESP.
• Blacklist vulnerability. If the IP is listed on a blacklist due to another sender's activity, your email may be blocked or deferred at receiving servers that reference that blacklist.
• Harder to diagnose issues. When inbox placement problems arise, it can be difficult to determine whether the root cause is your own sending behavior or that of a fellow user on the same shared IP.

What are the advantages and disadvantages of dedicated IP?

Advantages 

• Full reputation ownership. Your IP reputation reflects only your sending practices. Clean list hygiene, good engagement, and low complaint rates directly translate into a strong sender reputation.
• Isolation from other senders. No other organization's sending behavior can affect your deliverability. This isolation is especially valuable for high-stakes transactional email such as account alerts, password resets, and purchase confirmations.
• Better performance at scale. High-volume senders, typically those sending more than 100,000 to 200,000 emails per month, benefit from the consistency that a dedicated IP provides.
• Easier troubleshooting. When deliverability issues arise, the cause is almost always traceable to your own campaigns. This makes diagnosis and troubleshooting faster and more precise.

Disadvantages 

• Warm-up period required - A new dedicated IP doesn't have a reputation. Sending at high volumes before the IP is warmed up will trigger ISP throttling and filtering. Warm-up typically takes four to eight weeks of progressively increasing volume.
• Higher cost - Dedicated IPs carry an additional monthly fee from your ESP and require ongoing management investment. This additional fee may rarely be justifiable for lower-volume senders.
• Requires consistent sending volume - ISPs expect predictable traffic from known IPs. A dedicated IP that goes dormant or experiences erratic volume swings can lose its established reputation and require re-warming.
• Accountability falls entirely on you - Poor list hygiene, high spam rates, or bulk sending to un-engaged subscribers will directly damage your IP reputation with no buffer from a shared pool.

Which IP type should you use? 

Use a shared IP if: 

• You send fewer than 100,000 emails per month.
• Your sending volume is irregular or seasonal.
• You are new to email marketing and have not yet established list hygiene practices.
• You are working with a reputable ESP that actively monitors and manages shared pool quality.

Use a dedicated IP if: 

• You send consistently high volumes of emails, typically exceeding 100,000–200,000 emails per month.
• You are a seasoned sender and your list hygiene, engagement rates, and authentication (SPF, DKIM, DMARC) are already well-managed.
• You require strict separation between transactional and marketing email streams.
• You want full visibility and control over your sending reputation.

Conclusion 

Quick Reference Comparison