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Outlook signature table borders after 2512: the fix

Outlook signature table shows borders after the 2512 update? Microsoft’s fixed known issue, the restart step and the OneNote workaround.
The Sendoff team4 min read

If a table in your Outlook signature now shows grid lines, you are probably hitting a known issue in classic Outlook for Windows after the Version 2512 update. Microsoft lists it as fixed. Restart classic Outlook to pick up the change. If the borders stay, rebuild the table in OneNote using Microsoft's steps.

What the problem looks like

A signature that had no borders starts showing thin lines around its table cells. The table looks clean in Word, and you did not change it. Microsoft says that after classic Outlook updates to Version 2512, existing signatures add table borders.

Users in Microsoft Q&A report the same thing after pasting a table from Word into the signature editor. Thread 5684777, titled "Email Signature has just added borders to a table that did not have them as recently as 23/12/2025", has 16 answers.

What causes it?

Microsoft says Word started applying a non-zero border set to the table. Outlook uses Word as its rendering engine, so a table you create in an Outlook message gets the same border. Microsoft's test is to make a table in Word with no border, then paste it into OneNote or PowerPoint. The borders show up there too.

Which versions are affected?

Microsoft's documented issue covers classic Outlook for Windows only. In Microsoft Q&A thread 5835189, which reports the same borders in New Outlook, a Microsoft External Staff moderator wrote on 24 March 2026 that the only official article is for classic Outlook, and that they could not find documentation for New Outlook. If you see the problem in New Outlook, report it through Microsoft's feedback channels. The OneNote workaround below is documented only for classic Outlook.

How do I get the fix?

  1. Close and restart classic Outlook. Microsoft says the Word change was expected to reach Current Channel by Friday, February 6, 2026, and restarting classic Outlook picks it up.
  2. Open a new message, insert the signature, and check the table.

Microsoft's page does not name a build number. An MVP reply in thread 5693180 says Outlook Version 2601 (Build 19628.20166 Click-to-Run) fixed it as of 4 February 2026. That is a community report, so use it to check your version, not as a rule.

How do I rebuild the table without borders?

If the borders stay after the restart, use Microsoft's workaround. Build only the table layout in OneNote, then move your signature content into it. Microsoft warns that formatting the whole table in OneNote can cause problems with fonts and styles, which is why the steps fill the cells in Outlook.

  1. In OneNote, add a page to a section and select the option to add text.
  2. On the Insert ribbon, select Table and pick a size, for example 2 × 3.
  3. Merge cells if your layout needs it.
  4. Select the table, copy it, and paste it into a new Outlook message that already has your signature.
  5. If the borders are not visible on your signature, maybe because they are white, turn them back on.
  6. Resize the table cells to match the width of your signature.
  7. Copy the contents of each cell from the old signature into the new table.
  8. Fine-tune the formatting.
  9. Turn the border off for the new table.
  10. Select the fixed signature and press Ctrl+C.
  11. On the Message ribbon, select Include > Signature > Signatures. Replace the old signature with the new one and save.
  12. Delete the OneNote page.

What forum answers get wrong

Removing the table is not a fix. A commenter in thread 5693180 wrote that deleting the table does not solve it, and Microsoft's description says the same thing happens with any table created in Outlook.

Editing the signature HTML file by hand is also not Microsoft's workaround. A reply in thread 5693180 says changing the class does not remove the table tags. It only overrides their styling.

One user in thread 5684777 says saving the source Word file as .doc instead of .docx stopped the borders. Microsoft does not document that. Test it on a copy before you rely on it.

How Sendoff handles this

Sendoff builds signature tables with border="0" and no border style, except where you add a bordered card or a divider. That is set in the signature renderer. The bug starts when Outlook renders a table with Word's setting, though, and Sendoff has not been tested against every Outlook build. If borders show after you paste a Sendoff signature, follow the steps above.

Design your layout in the free email signature generator, or read the Outlook setup guide.

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