Rolling out 200 mailboxes across 67 domains for a B2B agency
A 14-person lead-gen agency moved off self-managed Workspace to Inboxlee. The migration timeline and lessons learned.
Rejwan Nirob·Nov 5, 2025·7 min readA 14-person lead-generation agency was running 200 cold-email mailboxes across roughly 50 domains, all self-managed on Google Workspace. Domain renewal was a spreadsheet. DNS was managed manually per domain. Warmup data lived in screenshots in Slack. They moved everything to Inboxlee over 6 weeks.
Why they moved
A missed renewal dropped 12 mailboxes from one client cohort overnight. The client was unhappy. The agency owner was furious. The next week, they trialled Inboxlee with 8 new mailboxes. Six weeks later, they had migrated everything.
The migration plan
- Week 1 - provision 20 new mailboxes through Inboxlee for the next client onboarding
- Week 2 to 4 - migrate existing domains to Inboxlee management, one client at a time
- Week 5 - consolidate 50 domains down to 67 (rebalanced to enforce 2-to-3 ceiling)
- Week 6 - connect all sending tools to Inboxlee API for unified warmup tracking
The savings
Direct Workspace pricing was $7 per seat per month. Inboxlee partner pricing is $2.50 per seat per month. Across 200 seats, that is roughly $10,800 per year saved. The bigger savings were operational - hours per week of DNS, renewal, and warmup tracking moved into one dashboard.
Agencies running 50+ mailboxes are the biggest beneficiaries of consolidation. The setup time pays back in weeks.
Talk to salesFrequently asked
How long does it take an agency to migrate from self-managed Workspace to Inboxlee?
Six weeks at the pace this case study ran: Week 1, provision new mailboxes for the next client onboarding. Weeks 2-4, migrate existing client cohorts one at a time. Week 5, rebalance to enforce the 2-to-3 mailbox-per-domain ceiling. Week 6, connect sending tools and unified warmup tracking. No downtime on any client during the migration.
How much does an agency save by moving 200 mailboxes from direct Workspace to Inboxlee?
Direct Google Workspace pricing runs $7 per seat per month. Inboxlee partner pricing is $2.50 per seat per month. Across 200 mailboxes that is roughly $10,800 per year saved. The operational savings (DNS, renewals, warmup tracking) typically exceed the direct cost savings.
Why does Inboxlee enforce a 2-to-3 mailbox-per-domain ceiling?
Our partner-program telemetry shows the fourth mailbox on a single domain drops Gmail inbox placement by roughly 27 percentage points compared to a 2-mailbox-per-domain baseline. The deliverability sweet spot is 2 mailboxes per domain (ideal) or 3 mailboxes per domain (acceptable). 4+ is the cliff and the wizard refuses to provision past it.
What is the biggest risk in moving cold-email mailboxes between providers?
Missed renewals during the transition. If a domain expires between registrars, the entire mailbox cohort attached to it disappears overnight. Inboxlee provisions with auto-renew enabled by default and surfaces 30-day expiry alerts; the agency in this case study migrated specifically because a missed renewal cost them 12 mailboxes from one client cohort.