Why are my marketing emails going to spam?

Usually authentication and reputation: Gmail and Yahoo now enforce bulk-sender rules requiring SPF, DKIM, and DMARC authentication, one-click unsubscribe, and a spam-complaint rate under Google's published 0.3% threshold. Miss those and your mail gets filtered or rejected outright — regardless of how good the content is.

Deliverability is now compliance-shaped: authenticate your sending domain, send only to people who actually opted in, honor unsubscribes instantly, and prune addresses that never engage — a list that ignores you trains inbox providers to bury you.

Treat it as infrastructure, not troubleshooting: check your domain's authentication once, monitor complaint rates in Google Postmaster Tools, and warm up any new domain gradually instead of blasting the full list on day one.