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GMass vs Sendbox in 2026: What Happens When You Outgrow the Gmail Send Cap
Here is how Sendbox and GMass stack up on pricing, infrastructure, and feature set. GMass operates as a layer on top of Gmail, backed by ColdSMTP, but that Chrome-extension foundation runs into real ceilings once volume grows.
The Verdict
GMass takes an altogether different starting point: a Chrome extension living entirely inside Gmail. That same simplicity is both its selling point and its ceiling. Composing happens in Gmail, contact lists live in Google Sheets, and ColdSMTP handles the actual infrastructure -- a setup that suits individuals and small teams sending under 10K emails a month reasonably well.
What it does not offer is a dedicated IP, a lead database, a dialer, or a unified inbox spanning multiple accounts. Sendbox, in contrast, is a complete platform built around dedicated IPs, isolated infrastructure, a 75K-email entry allowance, and a full tool suite in one place. For teams that have outgrown what Gmail can support, Sendbox is the natural next step.
Sendbox vs GMass: Feature-by-Feature
| Feature | |  GMass |
|---|---|---|
| Infrastructure | ||
| Dedicated IPs | Every plan Every plan comes with its own dedicated IP | No Mail routes out through Gmail's own infrastructure |
| Isolated Infrastructure | Yes Sending infrastructure is fully isolated | No Runs on Gmail's shared sending infrastructure |
| Email Warmup | Unlimited, AI-powered AI-powered warmup ships with every plan | No No warmup feature exists; it leans on Gmail's own sender reputation |
| Inbox Placement Testing | Built-in Check inbox vs spam placement ahead of sending | No Placement testing is not available |
| Features | ||
| Google Sheets Integration | No Lists come in through CSV import rather than a native Sheets connection | Yes Mail merge connects natively to Google Sheets |
| Gmail Native | No Runs as its own standalone platform | Yes Operates entirely within the Gmail interface |
| Built-in Dialer | Yes Calling is built natively into the product | No No dialer feature is included |
| Lead Database | 350M+ contacts A lead finder ships built into the platform | No There is no database of leads to search |
| CRM | Yes A pipeline CRM comes built into the product | No No CRM is included; an outside tool is needed |
| Sending | ||
| Email Accounts | Unlimited Effectively unlimited, bound only by a fair-use policy typical accounts never reach | Per-account Each license ties to a single Gmail account |
| Monthly Emails | 75K to 2.5M Runs from 75K on Essential up to 2.5M on Agency | Gmail limits Bound by Gmail's own sending caps, roughly 500/day on personal accounts and 2K/day on Workspace |
| Scale | ||
| White-label | From $499/mo Full white-labeling unlocks on the Pro tier | No White-labeling is not available |
Switch to Sendbox
Dedicated IPs. Isolated infrastructure. From $99/mo.
Pricing Comparison
75,000 emails · 30,000 leads
Dedicated IPs, all tools included
250,000 emails · 100,000 leads
All deliverability tools + finder credits
500,000 emails · Unlimited leads
White-label, unlimited leads
2,500,000 emails · Unlimited leads
Dedicated account manager
GMassGmail limits emails · N/A leads
Single Gmail account, Chrome extension
Gmail limits emails · N/A leads
Advanced features, higher limits
Gmail limits emails · N/A leads
Team plan, shared templates, priority support
Pricing takeaway
GMass is dramatically cheaper at $25/mo for individuals. But it sends through Gmail with Gmail limits. Sendbox at $99/mo gives you 75K emails on dedicated IPs. These are fundamentally different products for different scales of operation.
Different Approaches
GMass and Sendbox are fundamentally different products. GMass is a Chrome extension that adds cold email capabilities to Gmail. You compose emails in Gmail, use Google Sheets as your contact database, and send through Gmail infrastructure (or ColdSMTP).
It is designed for people who want to stay inside Gmail. Sendbox is a standalone platform with its own infrastructure, dashboard, lead database, dialer, and analytics. It is designed for teams that need a dedicated cold email system.
This means the comparison is not apples-to-apples. GMass is for individuals and small teams who want to add cold email to their existing Gmail workflow. Sendbox is for teams that need infrastructure-level control over deliverability.
Key takeaways
- GMass: Chrome extension that works inside Gmail
- Sendbox: standalone platform with dedicated infrastructure
- GMass: best for individuals adding cold email to Gmail
- Sendbox: best for teams needing infrastructure control
Gmail Limitations
Sending through Gmail means you inherit Gmail's limits: around 500 emails/day on personal accounts, 2,000/day on Google Workspace. GMass offers ColdSMTP as an alternative SMTP service, but that is still shared infrastructure. Sendbox starts at 75K emails/month on dedicated IPs with no Gmail dependency.
For teams sending more than a few thousand emails per day, Gmail limits become a real constraint. GMass works around this with scheduling and throttling, but you cannot fundamentally exceed Gmail's caps without ColdSMTP.
Key takeaways
- Gmail limits: ~500/day personal, ~2K/day workspace
- ColdSMTP available but still shared infrastructure
- Sendbox: 75K to 2.5M emails/month on dedicated IPs
- GMass works within Gmail constraints
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Set up in 15 minutes. Dedicated IPs on every plan.
GMass for Gmail-Native, Sendbox for a Real Platform
We recommend GMass if you are an individual or freelancer sending under 2,000 emails/day, you want to stay inside Gmail, and you use Google Sheets for your contact lists. At $25/mo, it is the simplest and cheapest way to do cold email from your existing Gmail workflow. We recommend Sendbox if you are a team sending more than 5,000 emails/month, you need dedicated IPs for deliverability, and you want a built-in lead database and dialer.
The $99/mo entry point is higher, but it is a complete platform rather than a Gmail add-on.
Key takeaways
- Choose GMass if: individual/freelancer, under 2K emails/day, want to stay in Gmail, budget under $30/mo
- Choose Sendbox if: team sending 5K+ emails/mo, need dedicated IPs, want lead database and dialer
Pros & Cons
Sendbox
Strengths
- Dedicated IPs on every plan
- 75K to 2.5M emails/month (no Gmail limits)
- 350M+ lead database included
- Built-in dialer for cold calling
- Built-in CRM with pipeline tracking
- White-label from $499/mo
Limitations
- 4x higher entry price ($99/mo vs $25/mo)
- Not Gmail-native (requires learning a new platform)
- No Google Sheets integration
GMass
Strengths
- Cheapest option at $25/mo
- Works entirely inside Gmail (zero learning curve)
- Native Google Sheets mail merge
- Simple setup (Chrome extension install)
- Annual discounts available
Limitations
- Sends through Gmail (subject to Gmail limits)
- No dedicated IPs
- No lead database
- No built-in dialer
- No CRM
- No white-label
- One Gmail account per license
- Limited scalability beyond Gmail constraints
GMass Screenshots
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Got questions? We've got answers.
Still stuck? Talk to us →No. GMass sends through Gmail infrastructure or ColdSMTP, both of which use shared sending. Sendbox includes dedicated IPs on every plan starting at $99/mo.
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Every plan includes a dedicated IP. Cancel whenever you want.