Why

Single-channel (email-only) inbound at that volume is the *easiest* CRM problem to solve — there's no WhatsApp chaos, no DM scraping, no phone-log reconciliation. With 10+ people touching deals, your real risks are duplicate replies, no clear owner per inquiry, and no view of which deals have gone cold. You told me nothing about pipeline stages or deal size, which itself is the tell — nobody on the team can see the funnel today.

What you actually need

1. HubSpot Free CRM (free for unlimited users) — connect your team inboxes, every inbound email auto-creates a contact + deal, and every rep sees who owns what. Free tier handles your volume without forcing a paid upgrade.
2. One pipeline, five stages: New → Qualified → Demo → Proposal → Closed — do not let anyone add custom stages in week one. Required field on every deal: "Next step + date".
3. A habit — the Monday 30-minute pipeline standup — walk every deal stuck >14 days in one stage. Move it, reassign it, or kill it. With 10+ people this is the only thing that prevents the "I thought you were following up" problem.

Do this today

Go to hubspot.com → sign up for the free CRM → Settings → Inbox → connect your shared sales email → Sales → Pipelines → rename the default to "Inbound 2026" and set the five stages above. Assign one teammate as admin before you log off. By tomorrow morning every new email inquiry lands as a deal with an owner, and you can finally see how many of last week's 50-ish inquiries got a reply.

What to ignore

Skip HubSpot Sales Hub Professional ($100/seat/mo), Salesforce Sales Cloud, and Outreach/Salesloft — at single-channel email inbound, you do not need sequencing, forecasting AI, or enterprise permissions yet. Ignore anyone pitching ZoomInfo or Apollo "to scale pipeline"; you already have 200–500 inbound/month, outbound tooling is solving the wrong problem. Pipedrive is fine too, but it charges per seat — at 10+ people, HubSpot Free wins on math alone.

What doing nothing costs you

A conservative 15% slippage on 350 inquiries/month (midpoint of your 200–500) = ~50 dropped inquiries monthly. For a SaaS product company, even a modest $3,000 ACV puts that at roughly $1.8M/year of pipeline leaking through unowned email threads.

When to revisit this

When two reps reply to the same inquiry in the same week, or when your deal volume in "Proposal" stops fitting on one screen — that's when paid tiers and proper forecasting start earning their keep.