Cold Email Shared vs Dedicated IP: 2026 Decision Guide

By Puzzle Inbox Team · May 26, 2026 · 8 min read

Should cold email use shared IPs from Google/Microsoft or dedicated IPs? Performance, cost, and decision framework.

Shared vs Dedicated IPs for Cold Email

IP reputation is one input to deliverability — domain reputation matters more for B2B cold email. The shared vs dedicated IP question depends on volume, sender history, and risk tolerance.

How Shared IPs Work

Default for most cold email infrastructure:

• Google Workspace: Google's shared sending IPs
• Microsoft 365: Microsoft's shared sending IPs
• SMTP services: pool of shared IPs

You inherit IP reputation built by all senders on the same IP.

How Dedicated IPs Work

Your sending traffic uses an IP no other senders use:

• Available on premium SMTP (SendGrid, Mailgun, Postmark)
• Available on Microsoft 365 with Exchange Online Plan 2
• Not available on standard Google Workspace

Shared IP Pros and Cons

Pros

• Free (included in subscription)
• Inherits established IP reputation
• Works at low volume
• No warmup needed

Cons

• One bad sender hurts everyone
• No control over IP reputation
• Reputation can change suddenly

Dedicated IP Pros and Cons

Pros

• Full control over IP reputation
• Isolated from other senders
• Better for compliance documentation
• Required at very high volumes

Cons

• Cost: $40-200/month per IP
• Requires warmup (4-12 weeks)
• Insufficient volume can hurt reputation
• Setup complexity

Volume Threshold

Dedicated IP makes sense above ~100,000 emails/month per IP. Below that, insufficient volume to maintain reputation.

Below 100k/month: shared IP from premium provider (Google Workspace, Microsoft 365) outperforms dedicated.

For Cold Email Specifically

Most cold email volumes are too low for dedicated IPs:

• 30 inboxes × 20/day × 22 days = 13,200/month — way below dedicated threshold
• 100 inboxes × 20/day × 22 days = 44,000/month — still below
• 500 inboxes × 20/day × 22 days = 220,000/month — above threshold but per-IP volume still low

Cold email scales through inbox count on shared IPs, not single IP volume.

Domain Reputation > IP Reputation

For B2B cold email, domain reputation drives 60-70% of inbox placement, IP reputation 20-30%. Domain warming (and authentication) matters more.

When Dedicated IP Makes Sense for Cold Email

• You're at 500k+ emails/month per IP
• You need compliance documentation (regulated industries)
• You've had bad shared IP experiences
• You have premium SMTP infrastructure

When Shared IP (via Google/Microsoft) Wins

• Volume below 500k/month per IP
• Standard B2B cold email
• Want to focus on domain reputation
• Cost-sensitive

Premium Shared vs Cheap Shared

Not all shared IPs are equal:

• Google Workspace shared IPs: highest reputation, premium senders
• Microsoft 365 shared IPs: high reputation, enterprise senders
• Cheap SMTP shared IPs: low reputation, mixed senders

Cheap inbox providers using cheap SMTP (private SMTP, Maildoso, etc.) inherit poor shared IP reputation.