The Role of IP Reputation in Email Deliverability
Every email you send originates from an IP address. That IP address has a reputation with email providers, and that reputation influences whether your emails reach the inbox.
Every email you send originates from an IP address. That IP address has a reputation with email providers, and that reputation influences whether your emails reach the inbox.
What is IP reputation
IP reputation is a score assigned to a specific IP address based on the historical sending behavior from that IP. Email providers track the volume, bounce rates, spam complaints, and engagement patterns associated with each IP. High-reputation IPs are trusted. Low-reputation IPs are filtered.
Shared IPs vs dedicated IPs
When you use Google Workspace or Microsoft 365 for cold email, your emails are sent from a shared pool of IP addresses used by all customers on that platform. This means your IP reputation is partially determined by other senders sharing the same pool. The good news: Google and Microsoft maintain high-quality IP pools and actively police abusive senders. The IP reputation you inherit is generally positive. A dedicated IP gives you sole control over the reputation, but it requires consistent volume (usually 50,000+ emails per month) to maintain. For most cold emailers, shared IPs through major providers are the better choice.
How IP reputation affects cold email
If you are using Google Workspace or Microsoft 365 — which you should be — IP reputation is largely out of your direct control. Your domain reputation is the more important factor and the one you can actively manage through authentication, warmup, and good sending practices. If you are using a third-party SMTP relay like Amazon SES, IP reputation becomes your responsibility. New IPs need to be warmed up with gradually increasing volume, and any abuse can permanently taint the IP.
Monitoring IP reputation
Google Postmaster Tools shows IP reputation data for IPs that send to Gmail. Microsoft SNDS provides similar data for IPs sending to Outlook. Check both regularly.
The practical takeaway
For most cold emailers, the best strategy is to use Google Workspace or Microsoft 365 accounts on properly authenticated, warmed domains. This gives you access to trusted IP pools while you focus your energy on managing domain reputation — which has a bigger impact on your deliverability outcomes. Warm Inboxes provides Google Workspace accounts on fresh .COM domains with all of this handled.
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