The easiest way to send an email campaign
GMass is a Chrome extension that turns Gmail into an email marketing and cold-email platform: compose a campaign directly in Gmail using a mail-merge list, with mass sending, deliverability tooling (Spam Solver, SPF checks, inbox rotation), sequences, and API/Zapier access.
The API details below are not linked to a current official developer page. Confirm them with the vendor before implementation.
| Plan | Price | Included | Notable |
|---|---|---|---|
| Individual — Standard | £23/month (or £15/month billed annually, £189/year) | — | Works inside Gmail, Send unlimited emails, Unlimited contacts and campaigns |
| Individual — Premium | £31/month (or £22/month billed annually, £265/year) | — | Everything in Standard, High-priority support |
| Individual — Professional | £46/month (or £37/month billed annually, £454/year) | — | Everything in Premium |
| Team — 5 users | £135/month (Premium) up to higher tiers per seat count | — | All Individual-plan features, Team-wide unsubscribe/bounce management |
| Team — larger seat tiers (10/25/50/100 users) | Ranging from roughly £225/month up to £1,670+/month depending on seat count and tier, per the pricing page's seat-count selector | — | All Individual-plan features at team scale |
Checked 2026-08-07 against their pricing page. Vendors change pricing without notice.
GMass is a Chrome extension ("GMass requires Chrome") that adds mass-email and cold-outreach capabilities on top of Gmail: build a list from a Google Sheet, personalize with mail merge, send campaigns at volume, track opens/clicks, and follow up automatically, with deliverability tooling (Spam Solver, real-time SPF checks, delivery routes) layered in. Because it runs inside Gmail rather than a separate send infrastructure, it inherits Gmail's sending limits, with an add-on SMTP server (ColdSMTP) offered for higher-volume cold email.
Individual senders and small teams doing cold email or email marketing who want to work inside Gmail rather than adopt a separate ESP, and who value deliverability tooling (spam checks, warmup-adjacent features, inbox rotation) over a full marketing-automation platform.
GMass is Chrome- and Gmail-dependent by design ("GMass requires Chrome"), so teams standardized on Outlook, a non-Chrome browser, or wanting a browser-independent sending infrastructure are not well served. Pricing scales sharply with seats within the Team plan (examples retrieved range from a handful of pounds per user at 5 seats up to roughly £1,670+/month at higher seat/volume tiers), so larger teams may find dedicated ESP or sales-engagement platforms with volume pricing more predictable.
No curated rival set covers this tool yet, so these are simply other tools in the same architectural layer and product form. Treat it as a starting point, not a shortlist.
The pricing page lists "API access (+Zapier)" as included on every plan, but we could not retrieve dedicated API reference documentation to confirm authentication, base URL, or endpoints.
That is an absence of evidence, not a confirmed absence; ask the vendor.
Yes - the product page states "GMass requires Chrome," and it functions as a Chrome extension that adds campaign-sending features to Gmail's compose window.
Per-user, Individual plans from £15/month (Standard, billed annually) up to £46/month (Professional, monthly); Team plans scale further by seat count, reaching roughly £1,670+/month at the largest tiers shown on the pricing page.
A separate sending-server product mentioned in GMass's own product changelog ("Meet ColdSMTP - our game-changing cold email sending server"), aimed at cold email use cases beyond standard Gmail sending limits. We could not retrieve dedicated documentation or pricing for it.
Spam Solver (AI-powered suggestions to hit the inbox), real-time SPF checks at send time, custom tracking links with SSL, and Inbox Rotation (MultiSend) across multiple sending addresses, per the product's own changelog and pricing page.
This page tells you whether GMass fits. Cheetah builds and runs the system it goes into — enrichment, sequencing, CRM and the joins between them.
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