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Comparison · Updated Mar 2026

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.

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Aryan S
By Aryan S
3 min readUpdated Mar 2026

At a glance

12 features
  • SendboxSendbox edge10
  • Tie0
  • GMass logoGMass edge2

Sendbox from

$99/mo

GMass from

$25/mo

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

Where it leads

Sendbox

  • Dedicated IPs on every plan
  • 75K to 2.5M emails/month (no Gmail limits)
  • 350M+ lead database included
GMass logo

Where it leads

GMass

  • Cheapest option at $25/mo
  • Works entirely inside Gmail (zero learning curve)
  • Native Google Sheets mail merge
On this page· 1/8
  1. The Verdict
  2. Feature Comparison
  3. Pricing
  4. Different Approaches
  5. Gmail Limitations
  6. GMass for Gmail-Native, Sendbox for a Real Platform
  7. Pros & Cons
  8. FAQ

Feature by feature

Sendbox vs GMass: Feature-by-Feature

Filter by category, or show only the rows where the two tools actually differ.

Sendbox vs GMass feature comparison
SendboxGMass
Infrastructure
Dedicated IPsSendbox
Every planEdge

Every plan comes with its own dedicated IP

GMass
No

Mail routes out through Gmail's own infrastructure

Isolated InfrastructureSendbox
YesEdge

Sending infrastructure is fully isolated

GMass
No

Runs on Gmail's shared sending infrastructure

Email WarmupSendbox
Unlimited, AI-poweredEdge

AI-powered warmup ships with every plan

GMass
No

No warmup feature exists; it leans on Gmail's own sender reputation

Inbox Placement TestingSendbox
Built-inEdge

Check inbox vs spam placement ahead of sending

GMass
No

Placement testing is not available

Features
Google Sheets IntegrationSendbox
No

Lists come in through CSV import rather than a native Sheets connection

GMass
YesEdge

Mail merge connects natively to Google Sheets

Gmail NativeSendbox
No

Runs as its own standalone platform

GMass
YesEdge

Operates entirely within the Gmail interface

Built-in DialerSendbox
YesEdge

Calling is built natively into the product

GMass
No

No dialer feature is included

Lead DatabaseSendbox
350M+ contactsEdge

A lead finder ships built into the platform

GMass
No

There is no database of leads to search

CRMSendbox
YesEdge

A pipeline CRM comes built into the product

GMass
No

No CRM is included; an outside tool is needed

Sending
Email AccountsSendbox
UnlimitedEdge

Effectively unlimited, bound only by a fair-use policy typical accounts never reach

GMass
Per-account

Each license ties to a single Gmail account

Monthly EmailsSendbox
75K to 2.5MEdge

Runs from 75K on Essential up to 2.5M on Agency

GMass
Gmail limits

Bound by Gmail's own sending caps, roughly 500/day on personal accounts and 2K/day on Workspace

Scale
White-labelSendbox
From $499/moEdge

Full white-labeling unlocks on the Pro tier

GMass
No

White-labeling is not available

Showing 12 of 12 features.

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Dedicated IPs. Isolated infrastructure. From $99/mo.

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Pricing

Pricing Comparison

SendboxAll-in-one

  • Essential

    Emails 75,000Leads 30,000

    Dedicated IPs, all tools included

    $99/mo

  • Plus

    Emails 250,000Leads 100,000

    All deliverability tools + finder credits

    $249/mo

  • Pro

    Emails 500,000Leads Unlimited

    White-label, unlimited leads

    $499/mo

  • Agency

    Emails 2,500,000Leads Unlimited

    Dedicated account manager

    $899/mo
GMass logoGMass

  • Standard

    Emails Gmail limitsLeads N/A

    Single Gmail account, Chrome extension

    $25/mo

  • Premium

    Emails Gmail limitsLeads N/A

    Advanced features, higher limits

    $35/mo

  • Professional

    Emails Gmail limitsLeads N/A

    Team plan, shared templates, priority support

    $55/user/mo

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

Start sending today

Set up in 15 minutes. Dedicated IPs on every plan.

Start Sending

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

Strengths & limitations

Pros & Cons

Strengths6

  • 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

Limitations3

  • 4x higher entry price ($99/mo vs $25/mo)
  • Not Gmail-native (requires learning a new platform)
  • No Google Sheets integration

Source material

GMass Screenshots

gmass.co
GMass homepage
Source: GMass (https://www.gmass.co)

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Your reputation, your control. No shared infrastructure.

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Keep reading

Sources

gmassG2Website

Cited sources

  1. Google: Google Postmaster Tools
  2. Google: Email sender guidelines
  3. Microsoft: Smart Network Data Services (SNDS)
  4. Microsoft: Email validation and authentication
  5. M3AAWG: Sender best common practices
faq

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.