Dedicated IP vs Shared IP: Which Should You Use?
A shared IP pools your sending reputation with other senders on the same address; a dedicated IP gives you an address nobody else sends from. Most businesses sending under roughly 100,000 emails a month are better off on a well-managed shared IP. A dedicated IP only pays off at consistent high volume, where your own behavior can carry the reputation.
What an IP reputation actually is
When your email hits Gmail, Outlook, or Yahoo, the receiving server checks several identities: the sending IP address, the sending domain, the authentication records attached to both, and the historical engagement associated with each. IP reputation is the score assigned to that numeric address based on complaint rates, spam-trap hits, bounce rates, and volume consistency over time.
That score is not permanent and it is not global. Each mailbox provider keeps its own view. Gmail may treat an IP as trustworthy while Microsoft throttles it. This is why "my IP reputation is fine" is never a complete answer to a placement problem.
Critically, IP reputation is only part of the picture. Domain reputation — tied to the domain in your From address and your DKIM signature — has become the heavier signal at most major providers. You can move to a brand-new dedicated IP and still land in spam if your domain has a bad history.
How shared IPs work
On a shared IP, your mail leaves from an address that many senders use. The provider manages that pool: they police who gets on it, they suppress senders with high complaint rates, and they keep the aggregate volume steady enough that mailbox providers see a stable, predictable stream.
The upside is real. Steady volume is the single hardest thing for a small sender to produce, and a shared pool produces it for you. Your 4,000-email newsletter arrives on an IP that already sends millions of messages a month with an established track record. You inherit that track record on day one.
The downside people worry about — "bad neighbors" — is mostly a function of how well the pool is policed. On a provider that enforces authentication, monitors complaint rates per sender, and removes abusers quickly, the neighbor risk is small. On a cheap provider that sells to anyone with a credit card, it is not.
How dedicated IPs work
A dedicated IP is yours alone. Every reputation signal generated from it is generated by you. That is the appeal: total control, no exposure to other senders, and the ability to build a reputation that follows your sending patterns precisely.
It is also the risk. A brand-new IP has no reputation at all, which providers treat with suspicion, not neutrality. You have to warm it up — sending small, gradually increasing volumes to your most engaged subscribers over several weeks — before you can send at full scale. And if your volume drops off between campaigns, the IP goes quiet and providers effectively forget you, so the next big send looks like a cold start again.
Side-by-side comparison
| Factor | Shared IP | Dedicated IP |
|---|---|---|
| Reputation source | Pooled across all senders on the IP | Entirely your own sending behavior |
| Time to full sending | Immediate | 2–6 weeks of warmup |
| Volume needed to work well | Any volume, including a few hundred/month | Consistent high volume, typically 100k+/month |
| Effect of an irregular schedule | Minimal — pool volume smooths gaps | Significant — gaps decay reputation |
| Neighbor risk | Present, mitigated by provider policing | None |
| Blocklist blast radius | Affects everyone on the IP | Affects only you |
| Troubleshooting clarity | Harder to isolate your own signal | Clean cause-and-effect |
| Ongoing effort | Low | Requires active monitoring |
| Typical cost | Included in plan | Add-on fee per IP |
When a dedicated IP is the right call
- You send high volume on a predictable schedule. Roughly 100,000+ messages a month, every month, not one spike in November.
- You send high-stakes transactional mail. Password resets, receipts, and order confirmations where a shared-pool hiccup is unacceptable. Separating transactional from marketing streams matters more than the shared/dedicated question itself.
- You need clean forensic data. If placement changes, you want to know it was your content or your list, with no confounding senders.
- A partner or compliance requirement demands it. Some enterprise agreements specify a dedicated sending address.
- You have someone who will watch it. Postmaster tools, blocklist monitoring, complaint feedback loops. A dedicated IP without an owner is a liability.
When a shared IP is the better choice
- You send under about 50,000 messages a month. There simply is not enough volume to establish and hold your own reputation.
- Your schedule is irregular. Monthly newsletters, seasonal promotions, and event-driven campaigns all leave reputation-decaying gaps.
- You're growing fast and don't want to manage warmup. A shared pool absorbs growth without a ramp plan.
- You have no deliverability specialist. The pool operator is doing that work for you, and doing it at a scale you cannot match.
Most senders in the $19/month-to-mid-market range fall here, and that is not a compromise. IGSendMail runs managed shared pools with automatic SPF, DKIM, and DMARC setup and 99% inbox deliverability — that combination beats an unwarmed dedicated IP in almost every real-world scenario.
The things that matter more than either choice
Teams reach for a dedicated IP when placement drops, and it is usually the wrong lever. Fix these first:
- Authentication. SPF, DKIM, and a DMARC policy aligned to your sending domain. Unaligned DKIM undermines everything downstream. Both Google and Yahoo now require authentication and one-click unsubscribe for bulk senders.
- List hygiene. Remove hard bounces immediately and suppress contacts who have not opened or clicked in 6–12 months. Sending to dead addresses is the fastest way to hit spam traps.
- Complaint rate. Keep it below roughly 0.1%. Above 0.3% and you will see throttling regardless of IP configuration.
- Consent quality. Purchased and scraped lists destroy reputation faster than any technical misconfiguration, and no IP strategy survives them.
- Subdomain strategy. Send marketing from
news.yourdomain.comand transactional frommail.yourdomain.comso a bad campaign cannot take down your receipts.
Run a full diagnostic before changing infrastructure — the email deliverability guide walks through the checks in order, and most placement problems resolve there without touching your IP at all.
How to warm up a dedicated IP if you go that route
Warmup is about teaching providers that your mail is wanted, using your most engaged subscribers as proof. A workable ramp:
| Stage | Daily volume | Audience |
|---|---|---|
| Days 1–3 | 50–200 | Opened in last 30 days |
| Days 4–7 | 500–1,000 | Opened in last 30 days |
| Week 2 | 2,000–5,000 | Opened in last 60 days |
| Week 3 | 10,000–25,000 | Opened in last 90 days |
| Week 4+ | Double every 2–3 days | Full active list |
Roughly double each step and hold if bounce rate rises above 2% or complaints exceed 0.1%. Warm each major provider separately — Gmail, Microsoft, and Yahoo respond at different rates, and Microsoft is typically the slowest to trust a new address. If you are routing application mail through an SMTP relay, keep that stream on its own IP or subdomain so warmup traffic and production traffic never blur together.
The practical decision
Start shared. Measure placement, complaint rate, and bounce rate for 90 days. If you cross 100,000 monthly sends on a consistent cadence and you have a person who owns deliverability, move to dedicated and warm it properly. If you are not there yet, spend the effort on list quality and authentication instead — that is where the returns actually are.
Frequently asked questions
How many emails per month do I need to justify a dedicated IP?
As a rule of thumb, around 100,000 messages a month sent on a consistent schedule. Below that, there is not enough volume to build and maintain reputation, and a managed shared pool will outperform it.
Does a dedicated IP guarantee better deliverability?
No. It gives you control over your reputation, not a better one. An unwarmed dedicated IP with poor list hygiene will land in spam far more often than a well-managed shared pool.
What happens if someone on my shared IP sends spam?
A reputable provider detects the complaint spike and suspends that sender, usually before pool-wide placement is affected. Risk is real but manageable — it depends almost entirely on how strictly the provider vets and monitors senders.
Can I use both a shared and a dedicated IP?
Yes, and it is a common setup. Many senders keep transactional mail on a dedicated IP for predictability while running marketing campaigns through a shared pool, each on its own subdomain.
How long does dedicated IP warmup take?
Typically two to six weeks, depending on your target volume and how engaged your list is. Microsoft-hosted domains generally take longest to build trust, so plan the ramp around the slowest provider, not the fastest.
Not sure which setup fits your volume? Launch on IGSendMail — automatic SPF, DKIM, and DMARC, managed sending infrastructure, and a free 24-hour migration from your current provider.