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I built a cold email platform with built-in inbox placement testing

I built a cold email platform with built-in inbox placement testing

by mainmin8t·Jul 11, 2026·1 point·0 comments

AI Analysis

MidSlick

Yet another cold email platform competing with Lemlist and Instantly.

Strengths
  • Seed mailbox network tests actual inbox placement across Gmail, Outlook, Zoho
  • Human-paced warm-up with reads, replies, and archiving mimics real behavior
Weaknesses
  • Cold email space is extremely saturated with established funded competitors
  • Deliverability features exist in Lemlist, Smartlead, Instantly already
Category
Target Audience

Cold email marketers, sales teams, growth hackers

Similar To

Lemlist · Instantly · Smartlead

Post Description

SpamCipher is a cold email platform I have been building. The part HN might find interesting is the deliverability layer: campaigns can run inbox placement tests against a network of real seed mailboxes (Gmail, Outlook, Zoho and others) that report whether your mail landed in the inbox or the spam folder, and mailbox warm-up engages with mail using human-paced reads, replies, and archiving. It also does email verification, DMARC monitoring, and blacklist checks.

If you want to poke at something without signing up, the spam checker at https://spamcipher.com/check is free.

Happy to answer questions. Running the seed mailbox network honestly has been the hardest part to build.

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