Warmbox and Warmup Inbox both warm up cold email mailboxes by trading real-looking engagement across a large inbox network — but they price and package it differently. Warmbox bundles several inboxes into flat monthly plans, while Warmup Inbox charges per inbox and offers a 7-day free trial. Here is which one fits your sending setup.
If you warm up a few mailboxes and want a flat monthly price, go with Warmbox. If you want to test before paying and scale mailbox by mailbox, go with Warmup Inbox.
| Tool | Starting Price | Inbox Network | Free Trial | Best For |
|---|---|---|---|---|
| Warmbox | $15/mo (1 inbox, 50 emails/day) | 35,000+ private inboxes | None listed | Agencies and teams warming 3-6 inboxes under one flat plan |
| Warmup Inbox | $15/inbox/mo (75 warm-up messages/day) | 30,000+ real human inboxes | 7 days, no card | Teams that want per-inbox pricing and a free trial first |
Price: $15/mo Solo (1 inbox) → $69/mo Start-up (3 inboxes) → $139/mo Growth (6 inboxes). Best for: Agencies and sales teams that warm up several mailboxes and want one dashboard with team members.
Price: $15/inbox/mo Basic (75 messages/day) → $49/inbox/mo Pro (250/day) → $79/inbox/mo Max (1,000/day). Annual billing saves 20%. Best for: Sales teams, SDRs, and recruiters who want to start small, test for free, and add mailboxes over time.
Warmbox sells bundles: $69/mo covers 3 inboxes and $139/mo covers 6. Warmup Inbox charges per inbox, so 3 inboxes on the Basic tier cost $45/mo billed monthly, but the same 3 on Pro cost $147/mo. Warmup Inbox gets cheaper per inbox with annual billing and volume, while Warmbox's flat plans are simpler to budget.
Warmup Inbox publishes clear per-inbox volume: 75, 250, or 1,000 warm-up messages per day. Warmbox lists plan-level limits of 50, 250, and 500 emails per day, so check which cap matches how many mailboxes you actually send from.
Both include deliverability reporting. Warmbox adds multiple schedule modes (growth, flat, random, custom) and a live email checker for DNS and blacklist status. Warmup Inbox watches 100+ blacklists daily and automatically works to recover listed domains.
Warmup Inbox lets you try the full plan for 7 days without a card. Warmbox lists no free tier or trial, so you commit from the first month.
Pick Warmbox if you manage a handful of mailboxes for clients and want team members and one flat price. Pick Warmup Inbox if you want to test first and pay per mailbox as you grow.
If you also need to send the campaigns, Smartlead combines unlimited mailboxes, warm-up, and AI agents in one platform.
Which is cheaper, Warmbox or Warmup Inbox? For one inbox both start at $15/mo. For three inboxes Warmbox is $69/mo flat, while Warmup Inbox is $45/mo on Basic or $147/mo on Pro.
Does either tool offer a free trial? Warmup Inbox offers a 7-day free trial with no credit card. Warmbox lists no free plan or trial.
Which supports more email providers? Both support Gmail, Outlook, Yahoo, Zoho, and custom SMTP. Warmbox also lists iCloud, Sendgrid, and Amazon SES, and Warmup Inbox also lists ProtonMail and Google Workspace.
Do I still need a separate tool to send emails? Yes, both are dedicated warm-up tools, so you run them alongside your sending platform.
Thomas
Founder
Thomas is the founder of AIPick.info and an avid AI enthusiast dedicated to testing and reviewing the latest tools. He believes technology should make life easier and more enjoyable for everyone. Beyond providing practical reviews, Thomas aims to build an uplifting space where AI feels accessible, delivering insights with energy, positivity, and a commitment to helping others innovate with a smile.
