File Format & Compatibility

How to Fix Word Corrupting Tables in HTM Files and Outlook Signatures

Maira Mehtab Sep 22, 2026 868 views

Question details

The user is encountering formatting issues where recent versions of Word and Outlook corrupt merged-cell tables in HTM files and HTML email signatures.

Product: Microsoft Word and Outlook
Device & OS: not provided
Scenario: Creating or rendering HTML email signatures that contain merged-cell table layouts.
Observed behavior: Table rows are incorrectly reset to two columns and column widths are altered when viewing the HTM files or rendering the signatures in Outlook.

Before you start

Before modifying your signature, open your email signature settings in Outlook or load the raw HTM file in a plain text editor like Notepad to review the current HTML structure.

Solution 1Recommended

Use Nested Tables with Fixed Widths Instead of Merged Cells

Restructure your HTML email signature by avoiding merged cells, which are poorly parsed by Word's HTML engine.

Microsoft Word's HTML parsing engine often struggles with colspan and rowspan attributes in merged cells, leading to layout breakage in Outlook. Replacing these merged cells with nested tables ensures maximum layout compatibility.

Open the HTM File

Right-click your email signature HTM file and select 'Open with' to launch it in a text editor like Notepad or a dedicated HTML editor.

Remove Merged Cells

Locate any <td> tags utilizing colspan or rowspan attributes and remove these attributes completely from your code.

Insert Nested Tables

Instead of merging cells, insert a new <table> tag within a single <td> element to construct complex grid layouts safely.

Define Fixed Widths

Apply explicit fixed widths using inline CSS (for example, style="width: 200px;") to every <table>, <th>, and <td> tag in the document.

Best Practice: Using nested tables with explicitly defined widths is the industry standard for ensuring email signatures render correctly across all desktop versions of Outlook.

Solution 2

Switch to RTF (Rich Text Format) Signatures Temporarily

If you need an immediate fix without editing HTML code, use Rich Text Format for your email signatures.

Solution 3

Optimize HTML with Inline CSS

Simplify your HTML code by applying inline styles directly to elements rather than relying on complex or deprecated HTML attributes.

Free Microsoft Office alternative

Try WPS Office for Seamless Document and Table Formatting

If Microsoft Word's HTML parsing limitations and table corruption issues disrupt your workflow, consider switching to WPS Office. It provides a highly compatible, lightweight alternative with robust formatting tools that handle complex table layouts reliably.

1. Download WPS Office: Visit the official WPS website and install the free office suite on your device.
2. Open Your Document: Launch WPS Writer and open your HTM or DOCX file to experience preserved table formatting.
3. Edit with Ease: Use the intuitive table tools in the Insert tab to create and manage complex layouts without compatibility issues.

Fully compatible with Microsoft Office formats including DOCX, XLSX, and HTML.Advanced table creation and formatting tools that prevent unexpected layout corruption.Free, lightweight, and easy to use with a familiar ribbon interface.Supports seamless migration from other office suites for a hassle-free transition.

microsoft office alternative - wps office

Frequently Asked Questions

Why does Outlook break my HTML email signature?

Outlook uses Microsoft Word's HTML rendering engine, which has limited support for modern web standards. It struggles particularly with merged table cells and complex CSS, often causing layouts to break or reset entirely.

What is the best way to format tables for Outlook signatures?

The most reliable method is to use simple, nested tables with explicit fixed widths applied to every individual cell via inline CSS.

Can I use external CSS stylesheets in Outlook email signatures?

No, Outlook frequently ignores or strips out external stylesheets and <style> blocks located in the HTML header. You must use inline CSS applied directly to your HTML elements to ensure the styles render correctly.

Does saving the signature as RTF solve the table corruption?

Yes, using RTF (Rich Text Format) bypasses the HTML rendering engine entirely, which avoids the HTML-specific table corruption issue, though it lacks some of the advanced design capabilities found in HTML.

Document & File Issues