What’s the difference between shared and dedicated IPs?

Imagine two restaurants sharing a kitchen. If one of them gets a health violation, the whole kitchen shuts down. That's roughly what can happen when you're on a shared IP and your ESP's pool neighbors start sending spam.

A shared IP means your emails go out from the same IP address as other senders on your ESP. The upside is real: you get a pre-warmed reputation from day one, it's included in your plan cost, and you don't have to manage anything. For most small and medium senders, this is the right choice. The tradeoff is that you're sharing that reputation. If another sender on your pool gets blocklisted or racks up complaints, your deliverability can take a hit even though you did nothing wrong.

A dedicated IP is yours alone. Your sending history is the only thing that shapes its reputation. That sounds ideal, and at the right scale it is. But it comes with two real catches. First, a brand-new dedicated IP has no reputation at all, which is almost worse than a bad one. You'll need to warm it up gradually before sending at full volume. Second, if you don't send consistently high volumes, the IP can go cold between sends and start looking suspicious to mailbox providers like Gmail and Outlook.

A rough guide on which to choose:

• Shared IP is usually the right call if you send fewer than 100,000 emails a month, you're just getting started, or you don't have the bandwidth to manage warmup and volume consistency yourself. A high-quality ESP with well-managed IP pools (like Postmark or Twilio SendGrid) keeps those pools reasonably clean.
• Dedicated IP makes sense if you're sending over 100,000 emails per month consistently, your sending volume is steady enough to keep the IP active, and reputation control matters enough to justify the extra cost and management overhead.

One thing worth knowing: some ESPs use IP pools to group senders by behavior, so even on a shared setup you may be alongside senders who look similar to you. That's meaningfully better than a fully mixed pool.

Not sure which applies to your setup? You can check if your current IP is on any blocklists with our free blocklist checker, or just ask us directly and we'll give you a straight answer.