CMass vs GMass
CMass now matches GMass feature-for-feature on sending — mail merge, sequences, send-as-replies, A/B testing, and reporting — then goes further with a built-in CRM, reply intelligence, and Claude. Here's the full breakdown.
TL;DR
CMass is a relationship intelligence platform built into Gmail— it tracks every contact's history and surfaces what to say next, with optional AI personalization on top. GMass is a solid, established mail-merge tool, but it stops at sending. If you want context on every relationship, CMass pulls ahead.
Feature comparison
Pricing
Where CMass pulls ahead
Relationship intelligence
CMass builds a full picture of every contact who engages — campaign origin, engagement history, a relationship score, and Claude-suggested talking points for your next message. GMass stops at sending; it has no equivalent.
Optional AI assist, no extra account
Want a personalized opener? Flip on the optional Claude assist — off by default, included in Pro, with no Anthropic account, API key, or per-token charges. GMass is limited to merge-tag substitution.
Built for Manifest V3
Chrome's new extension standard. CMass was built on MV3 from day one — which means better performance, better security, and no risk of being removed from the Web Store as Chrome phases out MV2.
Teams share history, not just lists
GMass team plans let you share campaigns and spreadsheets. CMass Team shares the relationship behind every contact — one pool where any seat sees the engagement, scores, and touchpoints from everyone's campaigns, so two reps never cold-email the same prospect. One unsubscribe protects the whole team.
Organizes replies, never deletes
CMass requests only the Gmail access its features need — send your campaigns, and read your threads to detect replies and apply organizing labels like "CMass/Replies". You're in control: reply labeling can be turned off anytime, and CMass never deletes your messages or touches mail unrelated to your campaigns. Your sent campaigns always land in your normal Sent folder.
Common questions
Does CMass work the same way as GMass — directly in Gmail?
Yes. CMass is a Chrome Extension that adds a panel directly inside Gmail. There's no separate web app to log into — your campaigns live next to your inbox.
Does CMass do more than merge tags?
Yes. CMass matches GMass on the core sending toolkit — Sheets/CSV mail merge, unlimited follow-up sequences, send-as-replies into an existing thread, A/B testing with an automatic winner, open/click/per-link/by-domain reporting, CSV export, and shareable report links. On top of that it adds a relationship intelligence layer: it tracks every contact's history, scores the relationship, reads reply sentiment, and suggests talking points. There's also an optional Claude AI assist you flip on per campaign for a tailored opening line — off by default. And the Reply Project gathers every campaign reply in one screen with one-click AI-drafted responses.
Do I need a Claude or Anthropic account for CMass's AI features?
No. CMass runs Claude on our infrastructure. You get AI personalization as part of your CMass Pro subscription — no extra accounts, no API key, no per-token charges on your end.
Can I import my GMass campaigns into CMass?
If your contacts are in Google Sheets or a CSV (which GMass users typically use), you can import them into CMass in minutes. Template content can be copy-pasted into the CMass template editor.
How does CMass compare to GMass for teams?
Both offer team plans. GMass team sharing is built around campaigns and spreadsheet lists. CMass Team shares the relationship layer: one pool of contacts where every seat sees the engagement history, relationship scores, and campaign touchpoints contributed by any teammate — so your team stops cold-emailing prospects a colleague already knows. Unsubscribes and bounces are suppressed team-wide, and a shared dashboard rolls up everyone's results. CMass Team is $49/mo for up to 5 seats and 2,000 emails/day.
Does CMass change anything in my Gmail account?
Only to help you stay organized, and only when you ask it to. With reply organization enabled, CMass applies labels like "CMass/Replies" to incoming campaign responses so you can triage them in your own inbox — the same approach GMass uses. CMass never deletes your messages and never archives or relabels mail you didn't send a campaign to. You can turn reply labeling off anytime from the extension, and your sent copies always land in your normal Sent folder.
Is GMass ever the better choice?
GMass has been around longer and has a large user base. If you only need basic mail merge and you're already comfortable with GMass, switching has a learning curve. CMass is particularly compelling for sales teams who want context on every relationship — engagement history, scoring, and talking points — not just a send button.
Ready to switch from GMass?
Free plan, no credit card. 50 emails/day to see if CMass works for your outreach before you commit.
Add CMass to Chrome — Free