Health Report
The health report is a practical QA layer for common email problems. It is not a replacement for human review or inbox testing.
What MailMode Checks
MailMode’s Health Report is split into quick signals and deeper diagnostics. It checks the rendered email, inbox preview copy, tracking, accessibility basics, dark mode readiness and selected client risks.
Small pills summarise the main risks immediately after preview.
Detailed cards explain rendering, inbox, tracking and client checks.
Warnings appear only when MailMode finds something worth reviewing.
Colours, Icons and Statuses
The report uses the same colour language throughout the app. The colour tells you how urgent the item is before you read the details.
No obvious problem was detected for that check.
Worth reviewing. It may be fine, but email clients can be unpredictable.
Likely needs attention before sending or sharing for approval.
Informational. Usually means there was nothing relevant to check.
Analysis Summary / Quick Scan
The quick scan is the compact row beneath the previews. It keeps the interface light while still surfacing the important checks.
Subject or preheader is missing, too short, too long, duplicated or suspicious.
No missing image alt text was found in the rendered email.
Shows whether UTMs, ESP tracking, click IDs or open pixels were found.
Counts links that MailMode can analyse without following them.
Total warnings and issues from the current report.
Full Health Report
The full report expands the quick scan into detailed cards. These cards are grouped by rendering, email health, tracking and potential issues.
Detailed rendering, tracking, accessibility, and client checks.
Rendered HTML size.
Looks for prefers-color-scheme rules.
Checks mode hints.
Detects Outlook selectors.
Rendering Checks
Rendering checks are static signals from the compiled email HTML. They do not guarantee inbox-perfect behaviour, but they highlight common dark mode and email-client risks.
Green when comfortably below Gmail clipping risk. Warning near roughly 85 KB. Issue above roughly 102 KB.
Checks whether the email includes prefers-color-scheme: dark rules.
Looks for colour scheme hints that tell clients the email supports light and dark rendering.
Checks for supported-color-schemes, a common email dark mode hint.
Detects Outlook dark mode selectors such as data-ogsc and data-ogsb. Neutral means they were not found.
Subject & Inbox Preview
This card checks whether MailMode can detect subject and preheader copy. Missing inbox copy is treated as an issue because it affects how the email appears before it is opened.
No subject or preheader was detected in this file.
Preheader not detected
HTML <title>, hidden preview text, MJML <mj-title>/<mj-preview>, or React Email <Preview>.
No subject was detected. In a real send, the subject may live outside the HTML, but MailMode cannot verify it unless present.
No hidden preview text was detected near the top of the email.
Very short copy may waste inbox space. Long copy may truncate, especially on mobile.
Repeating the same text wastes the preheader area.
Flags basic spammy language, excessive punctuation, too many emojis or all-caps subject lines.
Tracking Check
The Tracking Check scans links and image tags without making external requests. It reports what tracking is present and whether campaign tagging is consistent.
0 tracked links detected, 0 untracked links.
No obvious tracking consistency issues were found.
Usually means missing UTMs or open tracking pixels are present and worth reviewing.
Used for incomplete required UTMs, inconsistent UTM values or multiple tracking layers on the same link.
Links with UTMs, ESP click tracking, click IDs, affiliate parameters, CRM IDs or similar.
HTTP/HTTPS links with no detected campaign tracking.
Hidden, 1x1, transparent or tracking-keyword image URLs that may be used for opens.
Potential Issues
Potential issues are the general warning cards shown after rendering checks. If there are no warnings, MailMode shows an All clear card.
No warnings found in the rendered email.
HTML is approaching or over Gmail clipping size.
One or more images are missing alt text.
Script tags were stripped from preview.
Large emails can be clipped by Gmail, hiding content below the cutoff.
Most email clients block scripts. MailMode strips them from previews.
Forms are inconsistently supported in email clients and may fail.
Missing alt text affects screen readers and image-blocked inboxes.
Fixed widths above 640px can cause awkward scaling or clipping on smaller viewports.
Browser MJML cannot fetch included files. Inline included content before previewing.
Extra markup outside the main MJML root is ignored so the email can still compile safely.
Warnings from Gmail, Apple Mail, Outlook or Yahoo checks when a client preset is selected.
Client Check Warnings
Client presets add lightweight, client-specific warnings. These are still static checks, not real inbox screenshots.
Flags clipping risk, complex positioning/background image patterns and campaign links without UTMs.
Flags missing colour-scheme hints or dark-mode CSS, and reminds you that Mail Privacy Protection may affect open tracking.
Looks for Outlook dark selectors, MSO/VML fallbacks and background image risks.
Flags missing dark-mode fallback colours and wide fixed-width layouts.
How to Use the Report
Start with red issue cards, then review amber warnings. Green cards are useful confirmation, but they do not mean every inbox will be perfect. MailMode is designed to catch practical problems early so final inbox testing is faster and less surprising.