Your emails might be going to spam right now and you'd have no idea — here's why

Most SaaS founders discover their email deliverability is broken the worst possible way: a user replies saying "I never got my password reset" — days after the damage is done.

I built SendSurety after going through exactly this. Our welcome sequence was silently hitting spam for 11 days. Open rates looked "low" but not alarming. It wasn't until a user explicitly told us that we dug in and found a blacklisted IP and a broken DMARC record.

The scary part: none of our ESPs (SES, Mailgun) alerted us. They just logged "delivered" — because technically, they handed it off. What happens after that is invisible to them.

Curious — has anyone else here had a silent deliverability failure? Would love to hear how you caught it and what it cost you.