Connect InboxKit Mailboxes to Warmforge in Under 3 Minutes

Warmforge is Salesforge's warmup product, not Mailforge and not Primeforge. It runs a premium warmup network that only accepts real Google Workspace and Microsoft 365 accounts, no SMTP-based providers, no shared-IP senders. InboxKit connects via email + password, validates against Warmforge's auth endpoint, and pushes every selected InboxKit mailbox into the Warmforge pool in a single call. You do not paste SMTP credentials into InboxKit because Warmforge handles the per-mailbox OAuth inside its own dashboard after the initial connect.

Total connect time is under 3 minutes. This is the warmup to pick if you're running premium InboxKit mailboxes (Google Workspace or Microsoft 365, not shared-IP) and want blacklist monitoring + DNS checks layered on top of warmup in a single product.

Most warmup tools accept any SMTP mailbox. Warmforge is picky, the product team confirmed this directly on AppSumo: 'we only support Google Workspace and Outlook accounts, not SMTP-based connections. You can connect essentially only those two' (source). The reason is reputation isolation: Warmforge's aged-account pool is a premium asset, and letting SMTP users pollute it would degrade the pool's deliverability for everyone else.

Because InboxKit provisions real Google Workspace, Microsoft 365, and Azure mailboxes (not shared-IP pools), every InboxKit mailbox is eligible for Warmforge, which isn't true of shared-IP competitors like Mailforge. This is one of the practical reasons to pick a real-account infrastructure provider over a shared-pool one. See shared vs private email infrastructure for the full trade-off.

Get these ready:

Do not conflate Warmforge with Mailforge or Primeforge. This catches new users every week. All three products are in the Salesforge ecosystem but do different things: Mailforge is shared-IP cold email infrastructure (competitor to InboxKit on the mailbox side), Primeforge is real Google/Microsoft mailboxes (another competitor to InboxKit), and Warmforge is the warmup layer that sits on top of whichever infrastructure you use. You can use InboxKit mailboxes with Warmforge without paying for Primeforge or Mailforge. See Mailforge vs Primeforge breakdown for the ecosystem map.

The connect flow is standard email + password:

Total: about 90 seconds in InboxKit. After the InboxKit connect succeeds, you'll need to approve each mailbox's Google or Microsoft OAuth consent inside the Warmforge dashboard. This is a Warmforge-specific step: because Warmforge only works with Google and Microsoft, it uses per-mailbox OAuth at its own layer to maintain reputation isolation.

Once InboxKit has pushed the mailboxes, open Warmforge and finish the OAuth handshake for each one. Warmforge's onboarding video on YouTube walks through this exact flow for Google Workspace mailboxes.

Why this extra step? InboxKit gave Warmforge the credentials, but Google and Microsoft require an explicit per-user consent for any app touching their mailboxes via OAuth. InboxKit itself uses its own OAuth grants. Warmforge needs its own. This is the same reason the Lemlist integration forces OAuth for Google-managed domains: Google tightened SMTP AUTH policies in 2022 and the cleaner path is per-app OAuth.

The Google Workspace admin whitelist trap. If your workspace blocks third-party OAuth apps, the consent screen will show 'This app is blocked by your organization.' Fix: admin.google.com → Security → Access and data control → API controls → Manage Third-Party App Access → add Warmforge as Trusted. Skipping this step leaves the mailbox in 'Pending OAuth' forever.

Warmforge's differentiator is that it bundles warmup, DNS checks, and blacklist monitoring into one product. InboxKit's InfraGuard does something similar on the infrastructure side. Running both is not redundant. They check different things and catch different failures.

Run both in parallel and you have two independent watchers: Warmforge on the warmup/reputation side, InfraGuard on the DNS/domain-health side. They don't fight because they monitor different things. See email deliverability monitoring setup for the full monitoring stack recommendation.

Warmforge enforces its own warmup schedule, but when you move a mailbox from warmup-only to real outbound campaigns, use this ramp:

Google's Workspace outbound relay cap is about 2,000 per day but the cold-email practical ceiling is 40-50 per mailbox. For higher volume, add more InboxKit mailboxes horizontally instead of pushing any single mailbox past 50/day. See scale cold email 100 to 10000 for the mailbox-count math.

Do not double up warmup. Warmforge + InboxKit's isolated warmup + Instantly warmup running on the same mailbox is a reputation killer. Pick one warmup per mailbox, period. See domain warmup best practices for the full rule set.

Silent failure mode: Warmforge's dashboard can show a mailbox as 'Connected' even when the per-mailbox OAuth has been partially revoked. If counts suddenly drop to zero and status still says 'Connected', revoke and reauthorize the mailbox from scratch in Warmforge.

Test 1: Warmforge dashboard shows mailboxes. Open app.warmforge.ai → Mailboxes. Every InboxKit mailbox you pushed should appear within 60 seconds. Status should be 'Pending OAuth' initially, 'Warming up' after you approve OAuth.

Test 2: 48-hour warmup activity. After 48 hours, check each mailbox in Warmforge. You should see 10-20 sent, 8-15 received, 5-10 replied. If counts are zero, OAuth never completed or the daily limit is 0.

Test 3: Blacklist monitoring runs. Warmforge runs blacklist checks automatically. Within 24 hours of the initial connect, you should see at least one check result per mailbox in the Monitoring tab. If no results appear, the check loop is stalled, contact Warmforge support.

For deeper deliverability validation, run a Mail Tester or GlockApps test after 14 days of warmup. You're looking for 9/10+ on Gmail, Outlook, Yahoo, and Hotmail inbox placement. See inbox placement testing explained for full methodology.