What is a shared IP?
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When you send email through an ESP like Mailchimp, Brevo, or Mailgun, your messages don't go out from a server that belongs only to you. They go out from an IP address that the ESP shares across many different senders. That's a shared IP.
Think of it like an apartment building. The building has one address, but dozens of tenants live there. When a mailbox provider sees an email from that IP, it sees traffic from all those senders combined, not just you.
Your sender reputation on a shared IP is partly shaped by your own behavior and partly shaped by everyone else on that pool. If the ESP manages the pool well and keeps bad senders out, you benefit from a warm, established reputation right from day one. That's the upside. The downside is that a handful of bad actors on the same pool can drag the whole IP's reputation down, and your emails suffer for it even if you've done nothing wrong.
The alternative is a dedicated IP, where you're the only sender. Your reputation is entirely your own. But that only works if you have the volume to keep it warm (generally 50,000 to 100,000 emails a month is where it starts to make sense).
Most senders start on shared IPs, and for many, that's where they stay. A well-managed shared pool at a reputable ESP is genuinely a solid setup. The key word is well-managed. It's worth knowing which pool your ESP puts you on and whether they monitor it actively.
If you're curious about the trade-offs in more detail, the pros and cons of shared IPs are worth a read before you decide anything.
Want to check whether your current IP has any reputation issues? Our free blocklist checker will tell you in seconds.
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