Connect InboxKit Mailboxes to Warmy.io in Under 4 Minutes

Warmy.io runs one of the largest warmup networks in the category, with 650K+ domains, and its AI picks conversation partners from 30+ languages instead of the English-only defaults most warmup tools ship with. InboxKit connects to Warmy.io via email + password, validates the credentials against Warmy's auth endpoint, and pushes every selected InboxKit mailbox into the Warmy warmup queue. If you're running non-English outreach campaigns. Spanish, German, French, Dutch, anything in that range. Warmy's multi-language pool matters because the warmup traffic matches the language your real mailbox will send in.

Total connect time is about 3 minutes. The one step that trips up most new users is the Google Workspace admin whitelist. Warmy publishes a specific Google App ID that your workspace admin must approve in admin.google.com before the connection finishes.

Most warmup networks draw from a pool of mostly-English mailboxes. Warmy.io's own site states it 'supports warming up major email providers such as Gmail, G Suite, Google Workspace, Microsoft 365, Sendgrid, Amazon SES, Mailgun' and ships AI warmup in 30+ languages (source). The multi-language angle changes warmup training in a specific way:

Google's inbox classifier trains on what 'normal' looks like for your sending patterns. If the warmup is 100% English and your real campaigns are 100% Spanish, the classifier can flag a mismatch. Warmy avoids this by sampling its pool based on a language preference you set when you add the mailbox. This matters most for agencies running multi-region campaigns, see cold email infrastructure for Germany or France for the regional context.

Gather these:

The Google App ID whitelist step. Warmy.io's own help docs walk through this: 'Have your Google Workspace Administrator go to App Access Control, click "Configure new app", search for Warmy.io by using our Google App ID' (source). Without this step, Workspace tenants will reject the OAuth token Warmy needs to actually read and write the inbox during warmup. If you're on a trial Google Workspace account with no enterprise admin panel, this isn't required. Warmy's OAuth app is public. For legacy-managed tenants, the admin step is mandatory.

The connect flow is a standard email + password push:

Total: about 90 seconds in InboxKit. After the push, log into warmy.io to approve the per-mailbox OAuth connection (Google Workspace or Microsoft 365 consent screen) and pick the target language for each mailbox.

Once InboxKit has pushed the mailboxes, open Warmy and set the language preference for each one. This is the step that separates Warmy from most of the English-only competitors.

Warmy's AI will now sample warmup conversation partners from the subset of its 650K+ domain pool that speaks the selected languages. This takes effect immediately, the next warmup cycle uses the new language filter.

When to pick multiple languages. If you're running one mailbox that targets French-speaking prospects on weekdays and English-speaking prospects on weekends, pick both French and English. If you only send in English, leave it at English-only and you get the broadest pool. Multi-language selection is most useful for agencies running a single sender across European markets. See cold email infrastructure for Europe-wide campaigns for the regional breakdown.

Warmy.io's Gmail setup guide specifically calls out two settings that block most new connections: IMAP access and app passwords.

Warmy's own blog guide states: 'Generate an application password specifically for Warmy to ensure a smooth connection with your Gmail account. Enable IMAP access in your Gmail' (source). This is the SMTP fallback path. If the OAuth flow fails because the admin hasn't whitelisted Warmy's Google App ID, you can generate an app password in the mailbox owner's Google account and paste it into Warmy instead. It's slower but universally compatible.

InboxKit already provisions SPF, DKIM, DMARC, and MX via Cloudflare in under 60 seconds. See email authentication explained to verify the records manually, or cold email domain setup checklist for the full prerequisite list.

Warmy.io handles warmup, not real sends. Pair it with an outreach sequencer like Instantly, Smartlead, Reply.io, or Salesforge. Use this ramp when you move from warmup-only to real campaigns:

Google's cold email practical ceiling is 40-50 per mailbox. For higher volumes, add more InboxKit mailboxes horizontally, see scale cold email 100 to 10000 for the sizing math and email sending limits Google vs Microsoft for the provider caps.

Do not double up warmup systems. Warmy + InboxKit isolated warmup + Instantly warmup running simultaneously on the same mailbox is a reputation killer. Pick one per mailbox. See domain warmup best practices for the full rule set.

Silent failure mode: Warmy's dashboard shows 'Warming up' even when OAuth scopes have been partially revoked by a workspace admin policy change. If warmup counts suddenly flatline and status still says 'Warming up', reauthorize the mailbox from scratch.

Test 1: Mailbox appears in Warmy queue. Log into warmy.io → Mailboxes. Every InboxKit mailbox should appear within 60 seconds with status 'Warming up'. Missing mailboxes mean the push failed silently, check the InboxKit Exports page.

Test 2: 48-hour activity check. Expect 10-20 sent, 8-15 received, 5-10 replied per mailbox. If all zero, OAuth never completed or language is not set.

Test 3: Language-match verification. Open any of the warmup messages Warmy has sent from the mailbox (Warmy → Mailbox → Activity → View message body). The body should be in the language you selected. If you set French and the body is English, language preference didn't save.

After 14 days of consistent warmup, run Mail Tester or GlockApps. You're looking for 9/10+ inbox placement across Gmail, Outlook, Yahoo. See inbox placement testing explained for full methodology.