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Warmerly Folderly
One-to-one · Content and spam-trigger checks

Content and spam-trigger checks

One row, in depth: what each tool does, the verified numbers, and who each suits.

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Folderly details read from its pricing page, overview, home page, product sites, terms, privacy policy and help centre on 21 October 2026.

Warmerly

Free spam words and HTML checkers; pre-launch checks warn about spam-style copy.

Folderly

Detects Gmail and Outlook spam triggers; content analysis, a spam words checker, a send test (Flash) and an HTML preview (Mirror, beta).

The short answer

Content and spam-trigger checks, in one look.

Warmerly has free spam words and HTML checkers and pre-launch warnings about spam-style copy. Folderly audits the message as well as the sender: spam triggers in Gmail and Outlook, content analysis, a spam words checker, a send test (Flash) and an HTML preview (Mirror, in beta). Folderly is ahead on depth. Last checked 22 October 2026.

Warmerly

Free spam words and HTML checkers; pre-launch checks warn about spam-style copy.

FolderlyFolderly ahead on this row

Detects Gmail and Outlook spam triggers; content analysis, a spam words checker, a send test (Flash) and an HTML preview (Mirror, beta).

The picture

Drawn side by side.

What gets looked at

Sender, message and page

WarmerlyFolderly
WarmerlyBefore a campaign launches
  • Spam wordsA free checker
  • HTMLA free checker
  • Pre-launchWarns about spam-style copy
FolderlySend a testOn a test message
  • Spam triggersGmail and Outlook
  • ContentAnalysis and recommendations
  • Spam wordsA checker
  • FlashReviews a real send
  • MirrorHTML preview, beta

Folderly's Flash gives 3 free tests per IP per day.

Which layer each covers

As each company states it

WarmerlyFolderly

The sender

  • Warmup and DNS checks
  • A free spam words checker
  • Spam-style copy warning

The sender and the message

  • Spam triggers explained
  • A $19 Teardown, opening soon
  • Mirror prices marked indicative

Folderly's own pages describe the message-level tools. We have not tested them.

How Warmerly does it

Warmerly, in detail.

Free stand-alone checkers, and a warning before launch.

01

A free spam words checker

A spam word checker is one of the free tools, with no account needed.

Warmerly product, checked 21 October 2026

02

A free HTML checker

An email HTML checker is among the free tools.

Warmerly product, checked 21 October 2026

03

Pre-launch checks

A readiness check blocks a launch with no usable step or sender, and warns about DNS problems and spam-style copy.

Warmerly product, checked 21 October 2026

04

No message audit in the product

There is no content audit of a real test message, and no Gmail or Outlook spam-trigger report.

Warmerly product, checked 21 October 2026

05

A weighted list of 48 phrases

The spam words checker scores a subject and body against a curated list of 48 English phrases, each with a weight, such as click here at 8, urgent at 5 and unsubscribe at 3. Capital letters in over 60% of a subject of 6 or more letters add 12, and repeated ! or ? marks add 8. The score is capped at 100.

Warmerly product, checked 21 October 2026

06

Three risk bands

Below 15 is Low risk, 15 to 39 is Moderate risk and 40 or more is High risk. In a campaign, a step scoring 25 or more raises a warning.

Warmerly product, checked 21 October 2026

07

What the HTML checker measures

It reports the text-to-HTML ratio (under 5% is very low, under 15% is low), likely tracking pixels, image and link counts, and heavy inline styling over 15 style attributes. More than 10 links is a fail.

Warmerly product, checked 21 October 2026

08

Launch warnings use coarser counts

The pre-launch check uses simpler counts that run on the server: more than 5 links or more than 3 images in a step is flagged. The warning does not block a launch, but you must acknowledge it once before the campaign starts.

Warmerly product, checked 21 October 2026

09

Plain-text campaigns skip the markup checks

If a campaign sends plain text only, link and image counts are not flagged, because that markup is never sent. Spam wording still is.

Warmerly product, checked 21 October 2026

How Folderly does it

Folderly, in detail.

A set of content and rendering tools.

01

Spam triggers

Its page says the platform detects technical and content-based triggers in Gmail and Outlook, to show why emails land in spam.

folderly.com/overview · read 22 October 2026

02

Content analysis and a spam words checker

The overview lists content analysis and recommendations, and a spam words checker to detect and remove words that harm delivery.

folderly.com/overview · read 22 October 2026

03

Flash

Flash is a free send-readiness test: you send an email from your own tool and domain to a test address. The page lists 3 free tests per IP per day, and a $19 Teardown marked Opening soon.

flash.folderly.com · read 22 October 2026

04

Mirror, in beta

The home page labels Folderly Mirror Beta and says it previews email HTML. The mirror.folderly.com page describes a tool called Frame with Free, Lite, Pro and Agency tiers, marked indicative and pre-launch.

mirror.folderly.com · read 22 October 2026

05

Best practices and templates

It offers expert-backed deliverability tips for outbound and cold outreach, and a templates library in the app.

folderly.com/overview · read 22 October 2026

06

Flash returns a fixed-method score

Flash says the same email gets the same score within 3 points and that no LLM is in the scoring path. It says a test takes under 30 seconds and returns top fixes before technical detail.

flash.folderly.com · read 22 October 2026

07

What a Flash report contains

The free report lists a score and top fixes, a public share URL that needs domain ownership, domain history with trend and previous tests, a priority fix plan and a copy-ready fix brief. There is no sign-up, email gate or card.

flash.folderly.com · read 22 October 2026

08

What the Teardown adds

The $19 one-time Teardown lists a full forensic breakdown, every header explained and remediation copy, with a 7-day refund. It is marked Opening soon.

flash.folderly.com · read 22 October 2026

09

Mirror tiers and meter

The mirror.folderly.com page lists Free at $0 for 50 previews a month, Lite at $24 for 1,000, Pro at $69 for 2,500 and Agency at $149 with pooled previews, all marked indicative. The linter and deliverability score do not count against the preview meter, and active Folderly customers get it included.

mirror.folderly.com · read 22 October 2026

10

How Mirror renders

The page says Apple and iOS run through WebKit, and Gmail and Outlook.com through Chromium. Outlook desktop is rule-simulated, not rendered. Fidelity labels run from engine-accurate to real-client, and real-client is Pro only.

mirror.folderly.com · read 22 October 2026

11

A spam words checker listed for 9 languages

Inbox Insights' comparison table lists a spam words checker for 9 languages. The page does not name the languages, and the ticks are images.

folderly.com/email-deliverability-test · read 22 October 2026

What Folderly does not say

We looked, and found no statement on these. That is about its published pages only, not about the product.

  • Which specific content rules Flash applies
  • Whether Mirror and Frame are the same product
  • Prices for Mirror that are final
  • Which 9 languages the spam words checker supports
  • Which clients make up the core set on Mirror's Free tier
  • Independent evidence for Mirror's claim of catching 80 to 85% of breakage, which we do not use

Where the sources disagree

We report each version rather than pick one.

  • The home page calls the HTML preview tool Folderly Mirror. The page at mirror.folderly.com describes a tool called Frame. We treat them as one product, and we are not certain.
  • Mirror's page calls itself pre-launch in one place and says early access is open now in its FAQ. We treat its prices as provisional either way.
The numbers

Only what we could verify.

Content and spam-trigger checks: Warmerly and Folderly side by side. Warmerly is in the first column.
MeasureWarmerlyFolderly
Content and spam-trigger checksFree spam words and HTML checkers; pre-launch checks warn about spam-style copy.Detects Gmail and Outlook spam triggers; content analysis, a spam words checker, a send test (Flash) and an HTML preview (Mirror, beta).
Free Flash testsNone; free spam words checker3 per IP per day
Mirror previews on FreeFree HTML checker50 previews a month
Flash TeardownNo such product$19 one-time
Spam phrases in the checker48 weighted phrasesNot stated
Warning thresholdScore of 25 or moreNot stated
Flash result timeNot statedUnder 30 seconds
Mirror Lite price per 1,000 previewsFree HTML checker$24 a month
Mirror Pro price per previewFree HTML checker$0.0276 (69 / 2,500)
In practice

What it means for you.

Our reading of the facts above. Not a promise, and not the only reasonable reading.

1

Use the free tools on both sides

Both offer a spam words checker. Folderly adds a real-message review and an HTML preview.

2

Mirror is early

Folderly labels it beta and its own page shows indicative prices, so treat them as unfinished.

3

Scoring a subject line

With Warmerly's weights, a body containing click here once (8), urgent once (5) and act now once (8) scores 21, which is Moderate risk but under the warning level of 25. Add buy now (8) and it is 29, and the launch check warns.

4

Mirror volume maths

Lite is $24 a month for 1,000 previews, which is 2.4 cents a preview. Pro is $69 for 2,500, or 2.76 cents. All the Mirror prices are marked indicative and pre-launch, so treat these as provisional.

5

Three free Flash tests a day

Flash allows 3 tests per IP per day with no sign-up. Three drafts a day is enough to compare a plain version against a version with links and images. Warmerly's checker has no stated daily cap.

6

What neither checks

Neither a keyword score nor a render preview tells you how Gmail will classify a message. Flash says live placement appears only when seed inboxes report, and Warmerly's placement test is limited in accuracy until it has seed mailboxes.

Who it suits

Pick the one that fits.

Warmerly

Warmerly is the better fit if

  • You write your own copy and only want a warning before launch
  • You already use a message-testing tool
  • You mainly need warmup and campaigns
  • You want the check to run on every campaign step automatically, with an acknowledge step
Folderly

Folderly is the better fit if

  • You want your message reviewed, not only your mailbox
  • You want Gmail and Outlook spam triggers explained
  • You want HTML previews across clients
  • You want a fix plan and a copy-ready brief for a single message
Questions
Does Folderly check email content?

Yes. It lists content analysis and recommendations, a spam words checker, Gmail and Outlook spam-trigger detection, and Flash, a send test of a real message (read 21 October 2026). Warmerly has a free spam words checker and warns about spam-style copy before launch.

What is Folderly Mirror?

The home page labels Mirror as a beta tool that previews email HTML. The mirror.folderly.com page describes a tool called Frame, with prices marked indicative.

How does Warmerly score spam wording?

It adds the weight of each of 48 phrases found, times how often each appears, plus 12 for a mostly capital subject and 8 for repeated ! or ?, capped at 100. 25 or more raises a warning at launch.

What does Folderly Flash cost?

Flash's free verdict is 3 tests per IP per day with no sign-up. The Teardown is $19 one-time and marked Opening soon (read 22 October 2026).

Does Warmerly preview how an email looks in Gmail or Outlook?

No. Its HTML checker analyses markup, such as the text-to-HTML ratio, links, images and inline styles, but it does not render the email in different clients.

Sources

Folderly pages were read on 21 October 2026. Plans and wording change, so check the vendor's own page before you decide. Warmerly details come from the product as it runs today.

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