It reads like a template
Model-written notes lean on stock openers, empty compliments, and buzzwords. ColdLint marks those lines and gives a concrete edit for each one.
Lint your cold emails
before you hit send.
ColdLint is a spell-checker for the sequence you are about to load into Instantly, Smartlead, or Apollo. It marks AI-slop and spam-filter bait, checks the domain that will send it, and keeps a record of how that domain changes.
SequencesSpam riskSending domain
Lint this emailThe problem
A cold email fails in three ordinary ways. The copy sounds generated, the formatting looks like bait, or the sending domain cannot be verified.
It looks like spam bait
Trigger phrases, link shorteners, too many links, ALL CAPS, and a missing opt-out are the patterns the spam rules weigh before a sequencer sends.
The domain cannot be verified
If SPF, DKIM, or DMARC is missing, a receiver cannot verify the sender. If MX is missing, replies have nowhere to land. The lookup says which record is the problem.
How it works
1
Paste the note
Add the email, or a whole sequence split with a line of ---, and the domain that will send it.
2
ColdLint scans
Rules run on the server, and the domain is looked up live. Nothing is sent to a model unless you later press Rewrite, and that stays off until a key is set.
3
Get a verdict
Ready to send, Needs a pass, or Do not send. You also get the line edits and a plain-language note on SPF, DKIM, DMARC, and MX.
The verdict shows up here.
Scores run from rules on the server, so the same paste always lands in the same place. Nothing is sent to a model unless you later press Rewrite, and that button stays hidden until a key is configured.
- AI-slop, with a concrete edit for each flagged line
- Spam triggers, links, caps, and broken merge tags
- SPF, DKIM, DMARC, and MX in plain language
What it checks
The same rules run on every paste. A sequence is scored step by step, and the worst step sets the verdict.
AI-slop and generic openers
Stock greetings, fake compliments, and the vocabulary that shows up in model-written sales mail. Each flagged line gets an edit, not a vague “make it warmer.”
Spam words and formatting
Trigger phrases, ALL CAPS, stacked punctuation, and a missing opt-out. A short one-to-one note can skip the opt-out. A note that already sounds like a promotion should not.
Links and images
Shorteners such as bit.ly are flagged on their own. One normal link is fine. Two is a warning. Three or more is high risk. An image in a first touch is called out too.
SPF, DKIM, DMARC, and MX
Live DNS, explained in plain language. DKIM tries common selectors and says so when a custom selector would not appear. A failed lookup is a lookup error, not a missing record.
Length and readability
Under 20 words is thin for a first touch. Over 180 is long for cold email. Long sentences and a low readability score are part of the same pass.
Personalization
Double-brace merge tags such as {{firstName}} are left alone. Broken ones, including single braces and [First Name], are flagged because they ship as literal text.
A verdict, not a vibe
This short note is scored by the same rules as the checker. The clean lines underneath are the Clean note sample that ships with the product.
Example from the rule list: a note that opens with “I hope this email finds you well” is marked Do not send, with AI-slop 100 and spam risk 4. The Clean note sample is Ready to send, with AI-slop 0 and spam risk 4.
Before · A quick idea
After · Clean note sample
Priya, your March post said 40% of new managers stall on day 3 of onboarding.
Ready to send · AI-slop 0 · Spam risk 4
Built for the campaign, not a single paste.
The whole sequence
Paste every step, split with a line of ---. Each step gets its own slop and spam score. The worst step sets the verdict, so a clean opener cannot hide a sloppy bump.
The sending domain
SPF, DKIM, DMARC, and MX are looked up live and explained in plain language. You see what is missing before a sequencer starts sending.
The record over time
Pro saves the domain. A daily job rechecks it and writes down what changed: a new SPF include, DMARC moving off p=none, MX hosts swapping.
Who it is for
Anyone about to load a sequence into Instantly, Smartlead, or Apollo. No account is required for the free daily checks.
Founders
The first outbound notes, checked before they go into a sequencer.
SDRs
A sequence scored step by step, so a clean opener cannot hide a sloppy bump.
Agencies
A client’s copy and the domain that will send it, in one pass, with a share link.
AI-drafted outreach
A draft from a model, with the stock lines marked and a concrete edit on each.
Free and Pro
Free covers 3 checks a day, including sequences and a one-off domain lookup. Pro is $19/month: unlimited checks, a saved domain that gets rechecked, and rewrite when an API key is set.
Free
$0
- 3 checks a day, no account
- Whole sequences, scored step by step
- AI-slop highlights and a line-by-line rewrite suggestion
- Spam triggers, links, caps, and merge tags
- One-off SPF, DKIM, DMARC, and MX lookup
- Shareable result link
Pro
Most useful once a sequence is live$19/month
- Unlimited checks and sequences
- History of every lint
- Saved sending domain, rechecked daily
- A timeline of SPF, DKIM, DMARC, and MX changes
- AI rewrite that keeps your merge tags