Ephemeral Inboxes: Spin Up a Mailbox Per Test Run

Two CI workers kick off at the same moment. Both sign up a test user, both poll the shared QA Gmail account for "the" verification email, and worker #7 grabs the message that belonged to worker #12. The test passes. The wrong test. You spend an afternoon staring at a green build that should've been red. Shared inboxes are the single biggest source of flakiness in email-dependent E2E tests, and every workaround — catch-all forwarding rules, label rules scoped per PR, OAuth tokens living on the runner — adds another moving part that breaks on its own schedule. The fix is structural: every test gets its own address, on infrastructure your suite provisions and destroys. One wildcard, infinite addresses The E2E email testing recipe sets this up with one CLI command: nylas inbound create e2e You get back an inbox ID and a wildcard pattern shaped like e2e-*@yourapp.nylas.email . From there, each test mints a unique address under the wildcard — e2e-<uuid>@yourapp.nylas.email — and there's nothing to provision per address. You don't pay or configure per address either; the wildcard is just a convention, so burn UUIDs freely. Mail flows through MX records hosted on the Nylas side, which means zero DNS work in your own zone (the tradeoff: addresses live under *.nylas.email ). The Playwright fixture is two pieces — an address minter and a poller: export const test = base . extend < Fixtures > ({ testEmail : async ({}, use ) => { await use ( `e2e- ${ randomUUID ()} @yourapp.nylas.email` ); }, pollInbox : async ({ testEmail }, use ) => { const poll = async ( timeoutMs = 30 _000 ) => { const deadline = Date . now () + timeoutMs ; while ( Date . now () < deadline ) { const out = execSync ( `nylas inbound messages ${ process . env . INBOX_ID } --json --limit 50` , ). toString (); const match = JSON . parse ( out ). find (( m ) => m . to . some (( t ) => t . email === testEmail ), ); if ( match ) return match ; await new Promise (( r ) => setTimeout ( r , 1500 )); } throw new Error (