Built for serious email senders
CMass gives Claude everything it needs to write outreach that actually sounds like you — your data, your contacts, and soon your full relationship history.
Add to Chrome — FreeEvery list you have, in one click
Paste emails, upload a CSV, or link a Google Sheet directly. CMass auto-detects your email column and maps every other column as a merge tag automatically — {Company}, {Role}, {LinkedIn}, whatever you named it.
- ✓Google Sheets: link any sheet, no download required
- ✓CSV: drag-and-drop with instant column mapping
- ✓Paste: type or paste raw email addresses
- ✓CC and BCC columns: include stakeholders per row
Claude reads your data and writes something real
CMass is built on Claude — Anthropic's AI model. When you turn on personalization, Claude doesn't fill in a template. It reasons about each contact: their company, role, what column data you've included, and soon your meeting history and shared materials.
- ✓Claude writes one personalized sentence per recipient — not a spinner
- ✓Reads every column in your sheet: role, company, location, custom data
- ✓You write the email body, Claude adds the personal touch
- ✓Coming soon: reads your meeting history, shared decks, and attendee context
✦ ClaudeSaw TechCo just raised a Series A — congrats on the milestone.
I'd love to show you how CMass can help…
✦ AI Personalization
Claude writes one line per recipient
Unlimited automated follow-up stages
Set as many follow-up stages as you need. Each stage has its own timing, subject line, and send condition — only send to people who didn't open, didn't reply, or send to everyone regardless.
- ✓Unlimited stages — not capped at 3 like other tools
- ✓Per-stage conditions: no reply, no open, or always
- ✓Skip weekends option per stage
- ✓Threaded replies stay in the same Gmail conversation
Automated stages
Following up
Just wanted to resurface this…
Last touch
Don't want to be a bother, but…
Closing the loop
Closing this out on my end — let me know if…
See who opened, clicked, and replied
Real-time open and click tracking per recipient, per campaign. Know exactly who is engaging, when, and how many times — without leaving Gmail.
- ✓Per-recipient open and click counts
- ✓Campaign-level summary: sends, opens, clicks, bounces, unsubscribes
- ✓Reply detection: mark recipients who replied
- ✓Export data for reporting
Q2 Outreach — May 2026
Sent May 20 · 250 recipients
250
Sent
68%
Opened
16%
Clicked
4
Bounced
Keep your sender reputation clean
CMass automatically tracks bounces and unsubscribes so you never email a bad address twice. List-Unsubscribe headers are added to every campaign for one-click unsubscribe in Gmail and Apple Mail.
- ✓Automatic bounce suppression across all campaigns
- ✓One-click unsubscribe (RFC 8058) in every email
- ✓Bounce and unsubscribe lists are per-account and cumulative
- ✓CAN-SPAM and GDPR compliant out of the box
Tracking
Deliverability
12
Bounces blocked
3
Unsubscribes
Roadmap
Where CMass is headed
Email is just the surface. The real relationship lives in your meetings, the decks you shared, the follow-ups you promised, and the people who showed up. We're connecting all of it to Claude.
Google Calendar
Coming soonMeeting history per contact — date, duration, agenda, and whether it actually happened.
Meeting attendees
Coming soonWho was invited, who showed up, who didn't. Claude uses this to reference the right people.
Shared decks & docs
Coming soonLink a Google Drive folder. CMass knows what proposals and pitches you've shared with each contact.
Full email thread context
In progressClaude reads your email history per recipient. Coming: full thread summarization across campaigns.
Meeting notes & transcripts
PlannedConnect your recorder or notes app. Claude reads what was discussed, not just that a call happened.
CRM sync
PlannedPush CMass context to Salesforce, HubSpot, or Notion — and pull CRM fields into Claude context.
Start with what's live today. Everything above adds to the same Claude context — no workflow change required.
Add to Chrome — FreeCMass vs GMass
Same Gmail foundation. More power where it matters.
| Feature | CMass | GMass |
|---|---|---|
| Google Sheets mail merge | ✅ | ✅ |
| Unlimited follow-up stages | ✅ | ❌ |
| AI personalization per recipient | ✅ | ❌ |
| Arbitrary column merge tags | ✅ | ✅ |
| Bounce suppression | ✅ | ✅ |
| One-click unsubscribe (RFC 8058) | ✅ | ✅ |
| Open / click tracking | ✅ | ✅ |
| Per-stage send conditions | ✅ | ❌ |
| Skip weekends per stage | ✅ | ❌ |
| CC / BCC per recipient from sheet | ✅ | ✅ |