Nitrosend vs GMass.

Our own sending, agent-native, unlimited contacts, and a published price at scale.

TL;DR

GMass is a Chrome extension that turns Gmail into a mail merge and cold email tool. It sends from your own mailbox off a Google Sheet, with follow-ups that stop the moment somebody replies. If your sending is personal mail at scale and the answer has to land in your inbox as an ordinary thread, GMass does that well.

Nitrosend is a platform with its own sending rather than an extension on top of yours. Campaigns, flows, segments, and transactional sends run over a contact database you own. Every one of them is an email API endpoint and an MCP tool before it's a screen, so an agent can drive the stack without a person in a dashboard. Contacts are unlimited on every plan, including Free. Where it runs out: we don't send from your mailbox, so anything that has to read as a personal one-to-one email stays in GMass. Teams graduating from an extension to a platform usually read the GrowMeOrganic comparison, the iContact one, and the Inframail one next, and the full comparison index holds the rest.

Pricing math

What you actually pay.

The two ladders don't measure the same thing. GMass is priced per user with unlimited sending, and the sending is capped by the Google mailbox behind it. Nitrosend is priced per volume, with unlimited contacts on every rung. Monthly billing on both sides.

Scenario	Nitrosend	GMass
Free	8,000 emails to start, then 500/mo forever. Unlimited contacts, full MCP, API, and CLI	A seven-day trial at 50 emails a day, no card. No free plan after it
One sender, ~10,000 emails/mo	$20 Pro: 20,000 emails, unlimited contacts, 3 seats, BYO sending keys	$29.95 Standard: unlimited emails, one user, capped by Gmail at 500/day or 2,000/day on Workspace
100,000 emails/mo	$100 Ultra: 125,000 emails, unlimited contacts, 5 brands, 10 seats	$59.95 Professional: adds MultiSend rotation across Google accounts you already pay Google for. The GMass SMTP relay is free to 10,000/mo, then $5 per 10,000
A team of five	$100 Ultra: 10 seats, 125,000 emails, one bill	$175 Team: five Professional seats. Volume still comes from the five mailboxes

Prices accurate as of August 2026. Check vendor sites for current rates.

Migration

How to switch (or run both).

GMass keeps sending from your mailbox while you move, and there's a fair chance you'll want it to stay there for the one-to-one mail.

Add and verify your sending domain in Nitrosend. Its DKIM and SPF records sit alongside the Google records the mailbox already uses, so both can send from the same domain for as long as the overlap lasts.
Take the list out of the sheet. GMass campaigns run off Google Sheets, so the export is a sheet download. Import it with nitro_import_contacts, and a column of merge fields becomes a custom property rather than a spreadsheet header.
Bring the suppressions with it. Pull your unsubscribes through the GMass /api/unsubscribes endpoint before the first send, so nobody who opted out of a GMass campaign meets a Nitrosend one.
Rebuild the follow-ups as a flow with nitro_compose_flow. GMass follow-ups live on a campaign and stop on a reply. A flow lives over the contact record, so it can branch on what somebody did rather than only on whether they answered.
Decide what carries the sending. BYO sending keys on Pro and above route mail through your own transactional provider. There's no GMass credential to carry across, because GMass sends through the Google mailbox you already own rather than through a transport of its own. The Google records stay exactly where they are.

Honest credit

What GMass does well.

Picking a tool is about fit. Here's what GMass is genuinely good at.

Sends from the mailbox the recipient already knows, so a reply arrives as an ordinary Gmail thread in the inbox you already read.
Lives inside Gmail as a Chrome extension, so the compose window is the interface and there's nothing new to learn.
Google Sheets mail merge, where every column in the sheet becomes a personalization field.
Builds a list out of Gmail itself, pulling recipient addresses straight from a Gmail search.
Unlimited emails, contacts, and campaigns on every paid plan. GMass meters nothing; Google does.
Follow-up sequences that keep going until somebody replies.
MultiSend distributes one campaign across the Google accounts you've connected, with no surcharge for the volume that unlocks.
Schedules a large campaign across consecutive days to stay inside the daily quota rather than refusing the send.
Connects an external SMTP server, or the GMass relay, to send past the mailbox quota while keeping the Gmail interface.
A REST API that will create and send a whole campaign without the UI, plus webhooks on sends, opens, clicks, replies, unsubscribes, and bounces.
A Zapier app on the same events, with actions for a transactional send and an unsubscribe.
Free email verification and a Spam Solver included in the plan rather than sold as credits.

What Nitrosend adds

Where we think we're better.

Nitrosend does its own sending, so the ceiling is the plan you bought rather than a mailbox quota Google sets and throttles.
Campaigns, flows, segments, and transactional sends in one platform, over a contact database you own rather than a spreadsheet.
Unlimited contacts on every plan including Free, where GMass has no free tier at all after the trial, so a list that grows without being mailed never moves the bill.
Priced on volume rather than on seats, so the fifth and tenth person on the team costs nothing extra to add.
MCP-first is an architecture, not an integration: every capability is an API endpoint and an MCP tool before it's a screen.
The MCP covers campaigns, flows, contacts, templates, and segments, not a read-only slice of them.
Deliverability, billing, tests, and approvals are tools too, and they're the four that usually stop an automation dead.
A REST API and a CLI sit alongside the MCP, so nobody is forced through an agent to get work done.
Templates, suppression, events, and exports are first-class objects, so the state a program runs on lives in the platform.
BYO sending keys on Pro and above route mail through Amazon SES, Resend, Postmark, Mailgun, or SendGrid, on a domain you already warmed.
A published price at every rung, including 500,000 to over 4,000,000 emails a month, with no quote-only tier at the top.

Use case fit

When to pick which.

Pick GMass if

The email has to come from you personally and the reply has to land in your inbox as an ordinary thread. You work out of a Google Sheet and want it sending this afternoon. The job is recruitment, press, link building, or a one-off announcement rather than a running program, and the whole volume fits inside the Workspace quota you already pay Google for. None of those are close calls.

Pick Nitrosend if

Your sending has stopped being personal mail and become a program: a list you own, repeat campaigns, segments, and product email that goes out whether anyone is at a keyboard. It's the right call when you want the platform drivable by the agent you already run, or when you'd rather the bill tracked sending than headcount. The sharpest case is a team of five whose real problem is that nobody owns the list.

GMass vs Nitrosend - common questions.

Can Nitrosend send from my Gmail account?

No. Nitrosend does its own sending on a domain you verify, so mail arrives from the domain rather than from a person's mailbox, and replies come back to the reply-to address you set. That's also what lifts the daily ceiling: the limit becomes the plan you bought instead of the quota Google puts on a single mailbox.

Does Nitrosend have Gmail's 500-a-day limit?

No. That cap belongs to the Google mailbox GMass sends through: 500 a day on a regular Gmail account and 2,000 on Workspace, lower once Google throttles for account age or bounces. Nitrosend's ceiling is the plan instead, from a Free plan that starts at 8,000 emails to paid rungs above 4,000,000 a month, and BYO sending keys on Pro and above route through your own Amazon SES, Resend, Postmark, Mailgun, or SendGrid account.

Can I run GMass and Nitrosend together?

Yes, and for a lot of teams that's the right answer. GMass keeps the one-to-one mail going out of the mailbox, and Nitrosend runs the campaigns, the flows, and the transactional stream, each of them an MCP tool your agent can call rather than a screen somebody has to open. Both send from the same domain, with their authentication records side by side, so you can move one message type at a time and leave the rest alone.

Which works out cheaper for a team of five?

They're priced on different things, so it turns on what you're buying. GMass Team is $175 a month for five seats, with unlimited sending inside whatever quota the five Google mailboxes carry. Nitrosend's $100 Ultra carries ten seats and 125,000 emails. If your constraint is people, the seat price decides it; if it's volume, the send allowance does.

Start with the free tier.

8,000 emails to start, then 500 a month, unlimited contacts, full MCP, API and CLI access. No credit card.