Email + LinkedIn, one inbox, CRM as the record Every conversation in one inbox,
every outcome in your CRM.
The engine starts conversations across email and LinkedIn. Underfive brings all of them into a single inbox, classifies each reply, drafts the response, books the meeting, and writes the contact, the status and the outcome back to HubSpot or Salesforce. Nothing lives in a tool. The CRM is the record.
- Email + LinkedIn in one inbox
- Replies classified and drafted
- Synced to HubSpot and Salesforce
Underfive · underfive.ai 
Email VP Sales · fintech "send me a few times"
LinkedIn Head of RevOps "what does next week look like?"
Email CTO · healthcare "loop in our RevOps lead" → contact created
Email Director Ops "not now, try Q2"
Draft ready for 2 · median reply 3 m 40 s · 4 records written to CRM
LinkedIn reply
"Happy to chat next week"
Interested
Email reply
"Loop in our RevOps lead"
Referral · new contact created
CRM
Deal moved to Meeting booked
HubSpot · synced
2
Channels unified: email and LinkedIn, every thread with its history
< 5 min
Median time from reply to answer
100%
Of contacts, replies and outcomes written to HubSpot or Salesforce
How it works
Underfive in three steps.
- 01
Connect the channels
Inboxy mailboxes, AIA LinkedIn identities, LIA sequences and KALI invites all stream replies into one inbox with the originating signal attached.
- 02
Classify, draft, book
Interested, meeting request, referral, objection, out of office, not now. Each class gets a drafted response in your voice, and meetings land on the calendar.
- 03
Sync the CRM
Contacts, companies, activities, statuses and meetings are written to HubSpot or Salesforce as they happen. Your pipeline reports stay true.
Capabilities
Everything Underfive does.
Unified inbox
Email and LinkedIn threads side by side, with full history, the originating signal and the sending identity.
Reply classification
Sentiment and intent tags in seconds, with confidence scores and one-click override.
Drafted responses
Answers written in your voice from approved snippets, calendar availability and account context.
Meeting booking
Proposes times, sends invites through KALI, handles reschedules and no-shows.
HubSpot and Salesforce sync
Two-way sync of contacts, activities, statuses and meetings. Referrals create new contacts automatically.
Team workflows
Assignment by account owner, territory or round robin, approval rules per reply class, Slack alerts throughout.
Connects to HubSpot and Salesforce. Ships with an MCP server. Like every Vendisys product, Underfive writes contacts, activities and outcomes to your CRM, and exposes its capabilities to AI agents through MCP.
Where it sits in the engine
Underfive is one part of the complete outbound engine.
Use Underfive on its own, or connect it to the infrastructure layer and the other agents and the whole relay runs without manual steps. Vendisys has operated this engine for 2,200+ companies since 2002.
Which channels does Underfive unify?
Email and LinkedIn, natively from Inboxy, LIA, KALI and EMY, plus Instantly, Smartlead, HeyReach, GetSales and Aimfox.
Does it replace my CRM?
No. It feeds it. Underfive treats HubSpot or Salesforce as the system of record and writes every contact, reply, status and meeting there.
Does it send replies without a human?
Only for classes you mark as safe, such as out-of-office acknowledgements. Everything else is drafted and waits for one-click approval.
What about opt-outs?
Opt-out requests are detected on either channel, honoured across both, and synced to your CRM suppression lists automatically.
Underfive runs inside programs for teams at
And portfolio companies of
