PuzzleInbox vs Instantly Email Infrastructure
Dedicated inbox provider vs sending platform add-on. PuzzleInbox works with any tool — not just Instantly.
Should You Buy Inboxes from Your Sending Platform?
Instantly (instantly.ai) is primarily a sending platform that also sells inboxes as an add-on. This raises a strategic question: should you buy inboxes from the same company that provides your sending platform?
The Platform Lock-In Problem
Inboxes purchased through Instantly are tied to the Instantly ecosystem. If you switch platforms, your inboxes may not come with you.
Puzzle Inbox inboxes are standard Google Workspace and Outlook 365 accounts that connect to any sending platform via OAuth or SMTP/IMAP.
| Feature | Puzzle Inbox | Instantly Inboxes |
|---|---|---|
| Provider type | Dedicated infrastructure | Platform add-on |
| Platform flexibility | Any tool (OAuth/SMTP) | Tied to Instantly |
| Quality consistency | Uniform | Varies by source |
| Google Workspace | ✓ | ✓ |
| Outlook 365 | ✓ | Limited |
| Pre-warmed | ✓ | Some options |
| DNS control | Full visibility | Limited visibility |
Verdict: Separate your infrastructure from your sending platform. Buy inboxes from a dedicated provider like Puzzle Inbox and connect them to whichever sending tool fits your workflow.
Related Reading
- Best Cold Email Infrastructure Providers in 2026 — Honest Comparison — We evaluated the top cold email infrastructure providers on pricing, deliverability, Google Workspace support, and warmup — here's how they stack up.
- Why Your Cold Emails Land in Spam (And How to Fix It) — Your cold emails are landing in spam? Here are the 6 most common infrastructure problems causing it and exactly how to fix each one.
- SMTP vs Google Workspace for Cold Email — Why Infrastructure Type Matters — SMTP providers don't carry the same IP authority as Google Workspace. Learn why infrastructure type is the biggest factor in cold email deliverability.
- Cold Email Warmup: The Complete 2026 Guide — How to properly warm up cold email inboxes to establish sending reputation without getting suspended. Day-by-day protocol included.
- How Many Cold Email Inboxes Do You Actually Need? — A practical calculator for determining the right number of inboxes based on your email volume, ICP size, and meeting goals.