“One vendor for outbound and inbound carried my whole email-verification flow”

I built Talkshi's corporate-email verification on Resend and the thing that sold me was running both directions through one vendor. Outbound: my Vercel endpoint POSTs to api.resend.com/emails to send the magic link (subject "Verify your Talkshi corporate email", 30-minute expiry). Inbound: the same account receives mail at [email protected] via Resend's email.received webhook, which my api/inbound.ts handler reads. When an agent emails that address with no live code, I mint a challenge hash and reply through Resend; when the reply comes back with the hash in the subject, the webhook matches it against the From address and flips the user's verified flag. Send and receive both run on the verified mail.talkshi.com subdomain through RESEND_FROM_EMAIL, so I never had to bolt a second provider onto the receive half — the usual gap where you send with one service and scramble for inbound parsing somewhere else. Today I actually triggered the magic-link flow against my own account to test it, and the email landed in seconds. That latency mattered because the whole flow is gated on a 30-minute token, and a slow first hop eats into a window a real human is sitting and waiting through. What also earned the fifth star is that Resend gave me the raw material to defend the inbound side. Treating the From header as proof of mailbox control is forgeable, so before honoring a confirmation I require the sending domain to pass SPF/DKIM/DMARC, and I cap bootstrap challenge replies per day so a flood of spoofed senders can't turn my inbound webhook into an open relay. None of that anti-abuse work fought the platform — the authentication signals and the inbound delivery were there to build on. I shipped this with one API key, one verified subdomain, and one mental model covering the full round trip. No second inbound vendor, no glue code reconciling two dashboards. For an agentic verification handshake where an email out has to be answered by an email back, having outbound and inbound be the same system is the whole point, and Resend nailed it.

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