Why It Matters
Your sending IP address carries a reputation score with every major mailbox provider. If that IP has been used to send spam — even by a previous owner — your emails inherit that bad reputation. It's like moving into an apartment where the previous tenant never paid rent; the landlord's already suspicious. That's why the choice between shared and dedicated IPs matters so much for deliverability.
How It Works
Every email you send originates from an IP address. Receiving servers check that IP against blocklists, reputation databases, and their own internal scoring systems. Shared IPs (used by multiple senders on the same ESP) pool everyone's reputation together — one bad sender can drag the whole group down. Dedicated IPs give you full control over your reputation, but they require enough sending volume (typically 50,000+ emails per month) to maintain a stable reputation signal.
Quick Tips
- Check your sending IP's reputation using tools like Google Postmaster Tools, Sender Score, or Talos Intelligence before starting any campaign
- If you're on a shared IP and seeing deliverability issues, ask your ESP about their abuse policies — a lax provider means risky neighbors
- Dedicated IPs need warming; don't switch from shared to dedicated and immediately blast your full list, or you'll crater your new reputation