GMass vs Warmup Inbox: Cold Email Platform vs Email Warmup Tool Comparison
Compare GMass (cold email platform) and Warmup Inbox (email warmup tool) side by side. See pricing, features, and integrations to decide which one, or both, your stack needs.
GMass is a Gmail-based cold email platform starting at $29.95 per month, built for sending outreach campaigns with mail merge, follow-ups, and A/B testing. Warmup Inbox is an email warmup tool starting at $19 per month that builds sender reputation using a network of over 30,000 real inboxes. Many teams use both together.
Key takeaways
- GMass entry pricing starts at $29.95/mo for the Standard plan with unlimited emails, contacts, and campaigns inside Gmail.
- Warmup Inbox entry pricing starts at $19/mo on the Basic plan, which includes 75 warmup messages per day.
- Warmup Inbox exchanges natural-looking email with a network of more than 30,000 real inboxes to build sender reputation automatically.
- GMass integrates with Gmail, Google Sheets, Zapier, and Google Workspace, while Warmup Inbox integrates with eight platforms including Outlook, Zoho Mail, Amazon SES, Mailgun, SendGrid, and Sendinblue.
- Warmup Inbox's Max plan costs $99/mo and includes 1,000 warmup messages per day, while its agency tier starts at 15 inboxes with custom pricing.
Reviewed and updated September 2, 2026
GMass vs Warmup Inbox: Cold Email Platform vs Email Warmup Tool Comparison
GMass is a cold email platform; Warmup Inbox is an email warmup tool. Whether you need one, the other, or both depends on which part of the workflow you are buying for: cold email outreach on one side, email domain warming and deliverability on the other. This guide lays out what each vendor publishes.
The Quick Answer
GMass is a cold email platform for cold email outreach; Warmup Inbox is an email warmup tool for email domain warming and deliverability. By each vendor's own wording, GMass lists works inside gmail and unlimited emails, contacts, and campaigns, and Warmup Inbox lists email warmup and cold email sequence.
Warmup Inbox offers a lower entry point at $19/mo compared to GMass at $29.95/mo.
If your priority is sending campaigns that land in the inbox and generate replies, GMass is the one built for it; for building sender reputation and improving inbox placement, that is Warmup Inbox. Many teams run one of each.
Understanding the Core Difference
GMass is Gmail-based mass email and mail merge platform with unlimited emails, campaigns, and contacts directly inside Gmail.
Warmup Inbox is Email warmup service that exchanges natural-looking email with a network of more than 30,000 real inboxes to build sender reputation automatically. Also offers cold email sequences, language warmup, ESP warmup and IP warmup from the same dashboard.
The two platforms take different approaches to solving the same core challenge.
Pricing Comparison
Standard
Basic
GMass Pricing (as of September 2026)
| Plan | Price | Contacts | Emails |
|---|---|---|---|
| Standard | $29.95/mo | Unlimited | Unlimited (Gmail limits apply) |
| Premium | $39.95/mo | Unlimited | Unlimited (Gmail limits apply) |
| Professional | $59.95/mo | Unlimited | Unlimited (Gmail limits apply) |
| Teams (5 users) | $175/mo | Unlimited | Unlimited (Gmail limits apply) |
Source: GMass Pricing
Warmup Inbox Pricing (as of September 2026)
| Plan | Price | Contacts | Emails |
|---|---|---|---|
| Basic | $19/mo | per inbox | 75 warmup messages/day |
| Pro | $59/mo | per inbox | 250 warmup messages/day |
| Max | $99/mo | per inbox | 1,000 warmup messages/day |
| For agencies & teams | Contact Sales | Custom plans starting at 15 inboxes | custom |
Source: Warmup Inbox Pricing
Pricing Analysis
Warmup Inbox offers the lower entry point ($19/mo vs $29.95/mo). Teams watching their budget will appreciate the savings, especially when starting out.
Features Breakdown
- Works inside Gmail
- Unlimited emails, contacts, and campaigns
- Mail merge personalization
- Free email verification
- Automated follow-up sequences
- A/B testing
- and 4 more listed below
- Email warmup
- Cold email sequence
- Language warmup
- ESP warmup tool
- IP warmup
- Spam & Category monitoring
- and 3 more listed below
GMass Key Features
- Works inside Gmail
- Unlimited emails, contacts, and campaigns
- Mail merge personalization
- Free email verification
- Automated follow-up sequences
- A/B testing
- Spam Solver deliverability tool
- Custom tracking links
- Inbox rotation
- API and Zapier access
Warmup Inbox Key Features
- Email warmup
- Cold email sequence
- Language warmup
- ESP warmup tool
- IP warmup
- Spam & Category monitoring
- Email reputation Check
- Human-like AI generated content
- Developers API
The two lists below are a diff of each vendor's own feature list by exact wording, so a capability both tools offer can appear on either side under a different name.
Listed only by GMass
- Works inside Gmail
- Unlimited emails, contacts, and campaigns
- Mail merge personalization
- Free email verification
- Automated follow-up sequences
- A/B testing
- Spam Solver deliverability tool
- Custom tracking links
- Inbox rotation
- API and Zapier access
Listed only by Warmup Inbox
- Email warmup
- Cold email sequence
- Language warmup
- ESP warmup tool
- IP warmup
- Spam & Category monitoring
- Email reputation Check
- Human-like AI generated content
- Developers API
Integration Ecosystem
GMass Integrations
GMass connects with: Gmail, Google Sheets, Zapier, Google Workspace.
Warmup Inbox Integrations
Warmup Inbox connects with: Gmail & Workspace, Outlook & Microsoft 365, Zoho Mail, Amazon SES, Mailgun, SendGrid, Sendinblue (Brevo), Any inbox with SMTP.
Integrations listed only by GMass: Gmail, Google Sheets, Zapier, Google Workspace.
Integrations listed only by Warmup Inbox: Gmail & Workspace, Outlook & Microsoft 365, Zoho Mail, Amazon SES, Mailgun, SendGrid, Sendinblue (Brevo), Any inbox with SMTP.
Use Case Recommendations
Best Fit for GMass
- Budget-conscious teams looking for an affordable cold email platform
- Teams that need a wide feature set (10 capabilities listed)
- Sales teams running high-volume outbound email campaigns
- Agencies managing multiple client outreach programs
Best Fit for Warmup Inbox
- Budget-conscious teams looking for an affordable email warmup tool
- Organizations with complex tech stacks needing broad integration support (8 integrations)
- Enterprise buyers who prefer custom pricing and dedicated support
Feature Comparison Summary
| Feature | GMass | Warmup Inbox |
|---|---|---|
| Starting Price | $29.95/mo | $19/mo |
| Top Tier Price | $175/mo | Contact Sales |
| Total Features Listed | 10 | 9 |
| Integrations | 4 | 8 |
| Founded | 2015 | N/A |
Getting Started Checklist
- Define your cold email outreach and email domain warming and deliverability requirements and monthly budget
- Estimate your expected email sending volume and warmup email volume to find the right tier
- List the integrations your team currently relies on
- Sign up for free trials or demos of both platforms
- Run a small test with each tool before making a commitment
- Evaluate the onboarding experience and support quality
Final Thoughts
GMass serves the cold email outreach side of an outbound stack and Warmup Inbox the email domain warming and deliverability side. Warmup Inbox offers a more accessible entry point at $19/mo, while GMass starts at $29.95/mo. Your decision should weigh pricing against the specific features that matter most for your workflow.
Start with a trial of each to see which platform fits your team's daily process. The best tool is the one your team actually uses consistently.
Pricing and features verified as of September 2026. Visit GMass and Warmup Inbox for current information.
Frequently asked questions.
Frequently asked questions- What is the difference between GMass and Warmup Inbox?
- GMass is a Gmail-based cold email platform for sending mass outreach campaigns, mail merge, and follow-up sequences. Warmup Inbox is an email warmup tool focused on building sender reputation and improving inbox placement by exchanging email with a network of real inboxes. They address different parts of the outreach workflow, and many teams use both.
- Which is cheaper, GMass or Warmup Inbox?
- Warmup Inbox has the lower entry price at $19/mo on its Basic plan, compared to GMass's Standard plan at $29.95/mo. Warmup Inbox's pricing scales up to $59/mo for Pro and $99/mo for Max, while GMass scales up to $59.95/mo for Professional and $175/mo for a 5-user Teams plan.
- Do I need both GMass and Warmup Inbox?
- It depends on your goals: GMass handles sending cold email campaigns while Warmup Inbox handles building sender reputation and deliverability before or alongside those campaigns. The article notes many teams run one of each, since GMass focuses on outreach and replies while Warmup Inbox focuses on inbox placement.
- What integrations does GMass support compared to Warmup Inbox?
- GMass integrates with Gmail, Google Sheets, Zapier, and Google Workspace, four integrations total. Warmup Inbox supports a broader set of eight integrations, including Gmail and Workspace, Outlook and Microsoft 365, Zoho Mail, Amazon SES, Mailgun, SendGrid, Sendinblue (Brevo), and any inbox via SMTP.
- Who is Warmup Inbox best suited for?
- Warmup Inbox is best suited for budget-conscious teams looking for an affordable email warmup tool, organizations with complex tech stacks needing broad integration support across its eight listed integrations, and enterprise buyers who prefer custom pricing and dedicated support through its agency and teams plan.
About the author.
Tim Carden is CMO / CTO at RevenueFlow, which builds and operates outbound revenue engines for B2B companies. Studied at McGill University.
Tim Carden · CMO / CTO
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