Pre-send inspection — Stop — Audience swaps — Stop
Don't find out your newsletter got clipped from a reader.
MRNEWSLETTER checks your HTML against Gmail's clipping limit, scans for spam triggers, and previews your subject line on mobile — before you hit send. Then it matches you with newsletters your size to swap audiences with.
No credit card. 5 flight-checks a month, free.
- HTML SIZE
- 41.2 KB / 100 KB
- SPAM SCORE
- 4 / 100
- SUBJECT LENGTH
- 38 / 40 CHARS
before Gmail clips your email in the inbox
before your subject line truncates on mobile
tolerance for a verified swap match
The Pre-Flight Inspector
Paste your HTML. Get an instant readout on the three things that quietly wreck a send: Gmail clipping past 102KB, spam trigger phrases that tank your inbox placement, and subject lines that cut off on a phone screen.
- Byte-exact Gmail clipping check
- Weighted spam-trigger scoring with the exact phrases flagged
- Mobile inbox preview for subject line and preview text
<html><body>
<h1>This week in your niche</h1>
<p>100% free — act now!</p> ← flagged
</body></html>
Same niche · within 20% effective reach
The Verified Swap Exchange
Connect your ESP read-only. We verify your real subscriber count and open rate, then match you with newsletters in your niche within 20% of your reach — no more one-sided swaps where you send way more traffic than you get back.
- Read-only ESP connection — beehiiv, Kit, or Substack
- Matches ranked by how close their reach is to yours
- One click to request a swap, tracked with a UTM link
How it works
Paste your HTML
Before you hit send in your ESP, drop the exported HTML into MRNEWSLETTER.
Read the inspection
Gmail clipping, spam score, and a mobile inbox preview — one readout, ten seconds.
Fix it, then send
Go back to your ESP with confidence, or find a swap partner while you're at it.