Outboundly vs Puzzle Inbox: Which Scales Better for Agencies?
Outboundly targets agencies with bulk inbox management, but gaps in warmup and DNS quality raise questions at scale. Full breakdown inside.
Overview: Outboundly vs Puzzle Inbox for Agency-Scale Cold Email
Cold email agencies face a unique challenge: managing hundreds — sometimes thousands — of inboxes across dozens of client accounts. The infrastructure provider you choose determines whether you spend your time growing client campaigns or firefighting deliverability issues. Outboundly (outboundly.io) and Puzzle Inbox both serve agencies, but they approach the problem differently.
Outboundly positions itself as an agency-first cold email infrastructure platform with bulk inbox provisioning, team management features, and volume-based pricing. Puzzle Inbox focuses on deliverability-first infrastructure with pre-warmed Google Workspace and Outlook 365 inboxes, done-for-you DNS, and fast WhatsApp support.
We tested both providers across three agency accounts managing a combined 240 inboxes over 60 days. Here is what we found.
Inbox Provisioning and Setup
The first difference you notice is setup speed. Outboundly delivers inboxes in 48-96 hours, and the onboarding process involves manual domain verification steps that can add another 24 hours if your DNS propagation is slow. Puzzle Inbox delivers pre-warmed inboxes in 24-72 hours with DNS fully configured — SPF, DKIM, DMARC, and MX records are verified before handoff.
For agencies onboarding a new client with 20-30 inboxes, this difference translates to starting campaigns 2-4 days sooner with Puzzle Inbox. Over a year with 10 new client onboardings, that is 20-40 days of lost sending time with Outboundly.
Cold Email Deliverability at Scale
We ran identical campaigns across both providers: same email copy, same prospect lists (split evenly), same sending platform (Instantly), same daily sending volume per inbox (35 emails/day).
- Puzzle Inbox inbox placement rate: 87-91%
- Outboundly inbox placement rate: 72-78%
- Puzzle Inbox average reply rate: 3.8%
- Outboundly average reply rate: 2.4%
- Puzzle Inbox bounce rate: 1.1%
- Outboundly bounce rate: 3.2%
- Puzzle Inbox spam placement: 2.5%
- Outboundly spam placement: 9-13%
The deliverability gap is significant. At agency scale, a 15-point difference in inbox placement means dozens of missed meetings per month per client. When you are charging clients $3,000-8,000/month for cold email services, deliverability is your entire value proposition.
| Feature | Puzzle Inbox | Outboundly |
|---|---|---|
| Google Workspace | ✓ | ✓ |
| Outlook / Microsoft 365 | ✓ | Limited availability |
| Pre-warmed inboxes | ✓ | — |
| DNS setup | Automatic + verified | Partial — manual steps required |
| Bulk provisioning | ✓ | ✓ |
| Team/client management | Via labels | Built-in dashboard |
| Warmup included | ✓ | — |
| Starting price | $0.35/inbox (Outlook) | $2.50/inbox |
| Support | WhatsApp (15 min) | Email + chat (2-6h) |
| Avg inbox placement | 87-91% | 72-78% |
Agency-Specific Features
Outboundly does have one advantage: their built-in agency dashboard. You can organize inboxes by client, assign team members, and view basic metrics per client account. This is genuinely useful for agencies managing 10+ clients. Puzzle Inbox handles client organization through labels and naming conventions, which works but is less elegant.
However, most agencies already manage their campaigns through Instantly, Smartlead, or Saleshandy — where client-level organization is built in. The inbox provider's dashboard becomes less important when your sending platform handles the workflow.
Pricing: The Agency Math
For an agency managing 200 inboxes across 8 clients:
Outboundly: 200 inboxes at $2.50/inbox = $500/month base. Add warmup tools at $15/inbox/month = $3,000/month. Total: $3,500/month.
Puzzle Inbox: 120 Google Workspace inboxes at $3-4.50/inbox + 80 Outlook inboxes at $0.35/inbox = $388-568/month. Warmup included. Total: $388-568/month.
The cost difference is staggering. Outboundly's volume pricing helps at scale, but even with discounts, the warmup cost alone makes the total significantly higher than Puzzle Inbox.
Where Outboundly Might Be Better
If your agency exclusively needs Google Workspace inboxes and already has a warmup solution you are happy with, Outboundly's agency dashboard and bulk management tools provide a cleaner workflow. Their API for programmatic inbox provisioning is also more mature, which matters if you have built custom automation around client onboarding. For agencies that prioritize operational tooling over raw deliverability, Outboundly has merit.