I was cold emailing tons of real estate agents in Canada. One of them, top 20 in the country, replied, and I found his reply sitting in my spam folder.

It was the first message he’d ever sent me, and it went straight to spam. He had no idea. On his side he had answered me and that was the end of it.

If his mail does that to me, it does that to his clients too, and nobody ever tells you. You don’t get a bounce or a warning. You just stop hearing back, and then you decide people aren’t interested.

So I dug into why. It became a project with him and one of the top brokerage consultants in Canada, both of them selling for a living and losing deals to a folder nobody opens. We built a real platform: website, accounts, backend. Over 20 companies used it in beta, we audited over 300 emails, and we tracked over 2k DMARC reports.

What surprised me is how fixable it all was before the send. Most of the mail wasn’t spam. It was ordinary mail with something small and invisible wrong with it:

• A record that didn’t line up

• A subject that read like a promo

• Hidden white text the template put there

The sender could have fixed it in 2 minutes if anyone had told them which 2 minutes.

Then things didn’t go the way we planned and we split. I was the technical side. I built the checks, the scoring, and the DMARC pipeline, so I decided to stop it as a product and release the part that was worth something: the same engine that graded those 300 emails, now open source as a skill your agent runs (Claude Code, Codex, Cursor, Windsurf, or anything that reads SKILL.md).

What it does

1. Grade one email. Give it a message you sent or a draft. It runs 124 checks on the copy, SPF/DKIM/DMARC alignment, your domain records, 31 IP blocklists, 8 URL blocklists, and a live SMTP probe. You get a score, a verdict, and a list of what to fix.

2. Read your DMARC reports. These are the daily reports providers send about everything mailing as your domain. It shows who’s sending as you and gives you one next step. It won’t tell you to tighten your policy while a real sender of yours is failing alignment, because that would start rejecting your own mail.

No account, nothing uploaded, runs on your machine. You need uv, and each script pulls its own dependencies.

```git clone https://github.com/georgebnov/sendable.git ~/skills/sendable ln -s ~/skills/sendable ~/.claude/skills/sendable```

Honest limits. A good score means what you control is in order. Engagement and list quality still matter, and nobody can see which folder one specific person got. Any tool that claims to is guessing.

Fixing it before the send beats finding out after.

Repo: https://github.com/georgebnov/sendable

Run it on the last email you sent and tell me what it finds.