Dedicated IPs are one of the most oversold and most misunderstood purchases in cold email. Providers sell them as a deliverability upgrade. They are not. They are a control upgrade, and control only pays off above a certain volume, warmed correctly.
Here is the honest version: what a shared IP actually costs you, where the crossover sits, what warming really involves, and what the market charges.
What a shared IP actually costs you
On shared infrastructure your mail leaves on an IP that other senders also use. Their behaviour becomes part of your sending reputation, and you have no visibility into it and no ability to change it.
In practice that produces three failure modes:
- Unexplained placement drops. Open rates fall 30% in a week. Your copy did not change, your list did not change. Somebody else on the pool ran a bad campaign. You will never be able to prove this, which is the real problem.
- Blocklistings you did not earn. If the IP gets listed, every sender on it is affected, and delisting is the provider’s job on the provider’s timeline.
- Undebuggable deliverability. This is the one that actually costs money. When you cannot isolate the variable, you start changing things at random, new copy, new domains, new lists, and burn weeks.
None of that matters much at 2,000 sends a month. At 30,000 it is the dominant risk in the programme.
Where the crossover sits
| Monthly volume | What to use | Why |
|---|---|---|
| Under 5,000 | Google / Microsoft mailboxes | Not enough volume to build IP reputation. Platform trust beats control. |
| 5,000–20,000 | Either, or both | Judgement call. Split by recipient value: enterprise on Workspace, volume on dedicated IPs. |
| 20,000–100,000 | Dedicated IPs | Enough consistent volume to establish reputation, and enough at stake to need isolation. |
| 100,000+ | Multiple dedicated IPs, segmented | Separate IPs per campaign type or client so one problem cannot spread. |
The number that matters is not total volume but consistent volume per IP. An IP sending 500 a day every weekday builds reputation. The same IP sending 3,000 on Monday and nothing until Thursday does not, irregularity reads as suspicious.
Warming a dedicated IP, realistically
A new IP has no history. To an inbox provider that is not neutral, it is unknown, and unknown senders pushing volume look like spam sources. The warming process is how you build the history.
- Days 1–3: 20–30 sends a day. Send to engaged recipients, warmup networks, your own accounts, existing contacts, not cold prospects.
- Days 4–14: increase roughly 30% every two or three days. Introduce cold sends gradually, keeping engaged mail as the majority.
- Days 15–30: continue ramping toward target volume. Watch bounce rate and complaint rate at every step.
- Week 5–8: hold steady at target. The reputation is not stable until you have sustained consistent volume for several weeks.
Two rules. Never skip steps to hit a launch date, a burned IP costs more time than the delay would have. And watch the metrics, not the calendar: if bounce rate crosses 3% or complaints cross 0.1%, stop increasing and fix the list before continuing.
What providers charge
This is where the market is genuinely inconsistent, and where comparison tables mislead.
| Model | What you pay | The catch |
|---|---|---|
| IP as an add-on | Around $100 per additional IP, plus mailbox fees | Ten IPs adds $1,000 that never appears in the per-mailbox price you compared. |
| Shared pool | Cheapest per mailbox | No isolation. You are buying the risk described above. |
| Self-hosted | VPS cost only | You own PTR setup, blocklist monitoring, delisting and the 2am page. |
| IP included per mailbox | Mailboundry, from $2/mailbox/mo | None on price, but you still have to warm it properly. |
Infraforge, for example, charges $100 per additional dedicated IP on top of $4.00–$4.50 per mailbox per month. That is a defensible model, but it means a 50-mailbox setup running 10 IPs costs materially more than the headline per-mailbox figure suggests. Price the IPs separately when you compare.
Competitor pricing taken from public pricing pages at the time of writing. Prices change, verify current rates before you decide.
The setup that actually works at scale
Most teams past 50,000 sends a month land on the same architecture:
- Segment IPs by risk. Separate IPs for cold prospecting, for warm follow-up and for anything transactional. A cold campaign that goes badly should not touch the IP your booked-meeting confirmations leave on.
- Agencies: one IP set per client. Client A’s aggressive list cannot be allowed to damage Client B’s placement.
- Keep a Workspace pool. Reserve real Google or Microsoft mailboxes for named enterprise accounts where sender trust matters more than cost per send.
- Automate DNS. At forty-plus domains, hand-editing SPF records is the single largest source of silent failures. Bulk updates are not a convenience feature at that scale.
The short version
Under 5,000 sends a month, skip it, buy real Google or Microsoft mailboxes and spend the effort on your list instead. Past 20,000, a dedicated IP is the thing that turns deliverability from guesswork into a system you can debug. And when you compare providers, price the IPs as a separate line, because that is where the quoted per-mailbox rates stop being comparable.
Next: private infrastructure providers compared, or the real per-mailbox cost of Google Workspace.
Frequently asked questions
Do I need a dedicated IP for cold email?
If you send more than roughly 5,000 emails a month, yes. Below that you will struggle to generate enough consistent volume to build IP reputation, and the inherent trust of a shared Google or Microsoft mailbox serves you better. Above it, a dedicated IP is the difference between deliverability you can debug and deliverability you can only guess at.
How much does a dedicated IP cost?
It varies enormously by how it is packaged. Some infrastructure providers charge around $100 per additional IP on top of mailbox fees. Others include one per mailbox in the base price. Mailboundry includes a dedicated IP with every mailbox from $2 per mailbox per month, so the IP is not a separate line at all.
How long does it take to warm a dedicated IP?
Three to four weeks to reach meaningful volume, and about eight weeks before the reputation is genuinely stable. Start at 20 to 30 sends a day and increase roughly 30% every two or three days, watching bounce and complaint rates rather than following the schedule blindly.
Can a dedicated IP hurt deliverability?
Yes, in two situations. If you warm it too fast, a brand-new IP sending high volume looks exactly like a spam source. And if your volume is too low or too irregular, the IP never establishes a reputation and inbox providers treat it as unknown, which is worse than a well-behaved shared pool.
What is the difference between IP reputation and domain reputation?
IP reputation attaches to the server sending the mail; domain reputation attaches to the sending domain and follows it wherever you send from. Domain reputation is the more durable of the two and harder to repair. You need both, and a dedicated IP protects the one you can actually control day to day.