As much as I love and use Microsoft Products, they sometimes make bad decisions or introduce very annoying bugs. This article addresses a bug introduced on 16-Dec-2025 in Microsoft Outlook Version 2512 (Build 19530.20038 Click-to-Run) Current Channel.

The issue is that email signatures using a table will now have the border showing by default regardless of whether it was showing before the update.

The latest Microsoft 365 (Office) subscription update Version 2511 was released on 16-Dec-2025.

• Microsoft 365 Apps for Windows: Release notes for Current Channel

[Edit] As at 04-Feb-2026: The latest update Outlook Version 2601 (Build 19628.20166 Click-to-Run) does finally fix the issue.

The Problem

My email signature uses a borderless table to layout my logo, contact details, links to social media and professional recognitions in the manner I want them displayed.

After installing the latest Microsoft 365 (Office) update to my system I noticed that my email signature now had borders applied (even though I have not made any changes to it).

Looking at the Signatures and Stationery window (where you can create and edit signatures), it was now showing borders when it was not previously. Copying the original signature from Word (where the table had no borders) into an Outlook email or into the Signature Editor turns the borders on.

It also tries to change the fonts used to Aptos, but that is an entire separate issue. If you want to (mostly) get rid of Aptos font (as it is ugly and hard to read at 100% DPI), see:

• #MSOffice Changing the Aptos font back to Calibri in Microsoft Outlook

For every combination of steps I tried, the border would always be turned on in the signature editor and the editor itself does not offer the options to change any table settings.

I tried repairing my Microsoft 365 (Office) install, which completely removed and re-installed everything and the problem remained. I wanted to try rolling back the last update, but that was no longer possible after the repair!!

[Edit] See Workaround 6 for a really quick solution using Word to save as an old *.doc file to convert the type of table. Same end result as Workaround 4 and 5, but simpler steps.

[Edit] See Workarounds 4 and 5 below for steps to fix the issue either using NotePad.exe to edit the HTML file or using OneNote to create the table layout. Both methods achieve the same end result of changing the type of table used behind the scenes.

The Solution (Workaround 1) every time!

The solution I started using (hoping that Microsoft would fix the bug soon), on every single email I sent, perform the following steps:

1. Click in the table to select it.
2. Click on the square with the arrows at the top left of the table.
3. Click on the table border drop down arrow
4. Select No Border.

This method works fine but is wasting time on every email I send.

Looking for a better solution and also confirming that this was not just my problem, I did some searching and came across the following forum post from user MP007. The first answer did not help, so I added some clarifying comments with my experiences.

• Email Signature has just added borders to a table that did not have them as recently as 23/12/2025

There have been some ideas for solutions posted and, so far, the only one that actually provided a useful workaround was a comment on the original post from Jason on 06-Jan-2026.

The Solution (Workaround 2) except for Dark Mode?

Jason’s idea (which I have now implemented) was to leave the borders on (which we have no choice) but make them white. As long as the background is white (Page Color set to White or No Color), the white borders will disappear, except for when Dark Mode is used.

[Edit] Brian G pointed out that the white border method will fail if the recipients (or sender) are using Dark Mode on the computer (or phone) application. This was something I had not considered as I don’t use Dark Mode.

Here are the steps I used to make the changes.

1. With the signature (with borders) showing in an email.
2. Click in the table and the square with arrows should show at top left.
3. Click on the square with arrows to show the formatting bar.
4. Click on the drop down arrow next to the border button and select Borders and Shading.
5. On the Borders tab change the Color from Automatic to White and click OK.
6. Now highlight the signature can press Ctrl-C to place into clipboard.
7. From the Message ribbon, Include Section, select Signature >> Signatures …
8. Click at the top of the signature you want to edit and use shift-down arrow to highlight it. Ctrl-A does not work. Then delete it.
9. Paste in the “fixed” signature and remember to remove the extra lines added at the top and bottom of the signature.
10. Don’t forget to click Save to make sure the signature is saved.
11. Repeat for each account and signature you need fixed.
12. Click OK to close Signatures window.

I had to repeat this process 8 times for 2 signatures in 4 accounts. It will only work nicely when the background is white.

If replying to an email is using a page color, use the following steps to remove it:

1. Click on the Options Ribbon.
2. Click on Page Color.
3. Select No Color.

The Solution (Workaround 3) Never update again?

Piet Moen posted on the forum thread on 12-Jan-2025, a technique to successfully disable updates and roll back to the working version. I have tested his steps, and it did roll back Outlook to Version 2511 (Build 19426.20218 Click-to-Run).

[Edit] This appears to be the only true solution until Microsoft fix the bug.

1. Open Word and click on the Account button at the bottom left of the window.
2. Click on the Update Options button on the right hand side and select Disable Updates.
3. Make sure all Microsoft 365 (Office) applications are closed.
4. Open a Command Line (CMD) window using Run as Administrator.
5. Change the path with the following command:
   cd %programfiles%\Common Files\Microsoft Shared\ClickToRun
6. Execute the command to roll back to a specific version:
   officec2rclient.exe /update user updatetoversion=16.0.19426.20218

Once the updates have been downloaded and applied, your system will be back at the pre issue build. You might need to change your signatures back to No Border if you have used Workaround 2 above.

Also, as you have disabled updates, you will not be able to tell when the issue has been fixed. I will use another machine to retest after any updates and post here once I know the issue has been fixed.

Note: Rolling back to this version fixed both the performance issue on startup (showing Not Responding for up to 25 seconds) and the border issue.

[Edit] To turn updates back on follow the following steps:

1. Open Word and click on the Account button at the bottom left of the window.
2. Click on the Update Options button on the right hand side and select Enable Updates.
3. Click on the Update Options button on the right hand side and select Update Now.
4. Once the update has started, close all Microsoft 365 (Office) applications.

The Solution (Workaround 4) This works now!

Anthony commented on this post and notified me about another Microsoft Learn Forum Thread which has another solution from user called Alex.

• Outlook signature now has borders (table)

Here is the technique, it is a little technical but is less work than Workaround 5. It has been updated to replace the MsoTableGrid with MsoNormalTable rather than removing it. Workaround 5 used OneNote to achieve the same thing but might be more effort formatting the signature after the fix.

1. No need to close Outlook. Changes to the Signature are displayed when you next select it from the Message ribbon >> Include >> Signature >> XXXX.
2. Use Windows Explorer and go to the folder:
   %userprofile%\AppData\Roaming\Microsoft\Signatures
3. Locate the Signature file for your Signature (email account) with the .htm extension.
4. Edit this file using Notepad.exe or your preferred text editor.
5. Search for “class=MsoTableGrid” and remove it replace it with “class=MsoNormalTable” (there could be more than one instance).
6. Also, search for “mso-border-alt:solid” and replace it with “mso-border-alt:none” (there is likely to be more than one instance as it is probably at the table and cell level). If a cell is still showing a border, look for “mso-border-alt:” by itself as the “solid” might be on a separate line.
7. If needed, search for “border:solid” and replace it with “border:none” (there is likely to be more than one instance as it is probably at the table and cell level). If a cell is still showing a border, look for “border:” by itself as the “solid” might be on a separate line.
8. If needed, search for other “mso-border” tags, such as “mso-border-insidev:.5pt:solid” and replace it with “mso-border-insidev:.5pt:none” (there is likely to be more than one instance as it is probably at the table and cell level). If a cell is still showing a border, look for “mso-border-insidev:.5pt:” by itself as the “solid” might be on a separate line. (Thanks to Simon Archambault for the feedback)
9. Save the file.
10. Test the signature in an email.

[Edit] The steps above have been updated to include turning the borders off while editing the file as suggested by James Young on 23-Jan-2026.

[Edit] Thanks to Carl Tiede for the original PowerShell command (also including edits by Piet Moen) on 29-Jan-2026. This command can be used to change multiple users’ signatures automatically if used during the login process as a batch file.

[code]powershell.exe -command "gci "$env:APPDATA\Microsoft\Signatures" -Filter *.htm | ForEach-Object { (Get-Content $.FullName -Raw).Replace('class=MsoTableGrid','class=MsoNormalTable') | Set-Content $.FullName -Encoding utf8 }"

[/code]

Note: Using this script does not change the border tags from solid to none, but it does fix the table type. You might need to manually edit the borders (as per Workaround 1) and re-save the signature if the borders are not hidden, now that the table type has be fixed, changing the formatting should work as expected.

In the commands below, I have included further changing the “mso-border-alt:solid” and “border:solid” tags, if you have other tags or the tags go over a line break you might need to adjust the code, or make the changes manually.

[code]powershell.exe -command "gci "$env:APPDATA\Microsoft\Signatures" -Filter *.htm | ForEach-Object { (Get-Content $.FullName -Raw).Replace('class=MsoTableGrid','class=MsoNormalTable') | Set-Content $.FullName -Encoding utf8 }"
powershell.exe -command "gci "$env:APPDATA\Microsoft\Signatures" -Filter *.htm | ForEach-Object { (Get-Content $.FullName -Raw).Replace('mso-border-alt:solid','mso-border-alt:none') | Set-Content $.FullName -Encoding utf8 }"
powershell.exe -command "gci "$env:APPDATA\Microsoft\Signatures" -Filter *.htm | ForEach-Object { (Get-Content $.FullName -Raw).Replace('border:solid','border:none') | Set-Content $.FullName -Encoding utf8 }"

[/code]

The Solution (Workaround 5) This one works!

On 20-Jan-2026, Gabe Bratton from Microsoft Support has documented the known issue and provided a workaround that seems to work for all situations (including dark mode). The workaround was to use OneNote to create the table, rather than Word (or Outlook which uses Word as its editor anyway). This should create a more html “native” table rather than a “MsoTableGrid” table.

I initially tried to copy my existing signature from Word into OneNote and then select it and copy it back. This did fix the table issue but messed up the formatting. Notice that the borders turned on.

I did try to fix the formatting in OneNote, but the fonts (style, colour and size), line spacing and image layout were all wrong and it was too much effort, and I just could not get it to behave, especially getting the social media images back onto one line.

So, I changed tack and use OneNote to create an empty table layout and copied that layout into Outlook. Once in Outlook, I copied and pasted the contents of each cell from my signature into the new table. Then used that table as the new “fixed” signature.

Below are the steps I used to fix my signature using OneNote to create the table layout:

1. In OneNote, Add Page to a section and click to add text.
2. From the Insert Ribbon, select table and select the desired size. I used 2×3.
3. Once the table is added, merge any cells if needed.
   
4. Select this table and copy and paste it into a new Outlook message (that has your signature in it).
5. If the borders are not showing on your signature (maybe because they are white), turn them back on.
6. Now size the width of the table cells to match your signature.
   
7. Copy and paste the contents of each cell from the signature into the new table.
8. Fine tune any formatting. I needed to center align the left two cells with images and add two spaces between each of the social media images.
9. Turn the border off for the new table (as per Solution 1).
10. Select the fixed signature and use Ctrl-C to copy to the clipboard.
11. From the Message Ribbon, select Include >> Signature, Signatures …
12. Replace and Save all the signatures with this new “fixed” one. (as per Solution 2).
13. You can delete the OneNote page used to temporarily create the table layout.

This is actually achieving the same result as Solution 4 without editing HTML files directly. If you use the steps in Solution 4 to open the signature’s HTML file, you will see that it is now using “class=MsoNormalTable”.

The Solution (Workaround 6) This one is simple!

On 01-Feb-2026, Anerina posted a solution which is really simple and works beautifully. It is actually producing the same end result of converting “MsoTableGrid” tables to “MsoNormalTable” in the signature’s HTML file.

Here are the steps:

1. If the signature with a table is not already in a Word document, copy it into a new Word Document, otherwise open the Word document with the signature.
2. Select File >> Save As and same the document as a “Word 97-2003 Document (*.doc)” file.
3. You might get a warning about “Tables will lose alternative-text information”. Select “Continue” as that is exactly what we want it to do.
4. Now copy and paste the signature into Outlook and the table borders will work as desired.

Thanks for another solution that is really quick and easy to implement.

Steps to Reproduce

Using the following steps to test, I can confirm if the issue has been fixed.

1. In Outlook, start a new email.
2. Press Enter for a blank line.
3. From the Insert Ribbon, insert a 2 x 1 table.
4. Put a name into one cell and an email into the other cell.
5. Click on the square with arrows at the top left to bring up the formatting toolbar.
6. Click on the border drop down list and select No Border.
7. Select the table including a blank line above and below.
8. Press Ctrl-C to copy the “signature” with a no border table to the clipboard.
9. From the Message Ribbon, click Include >> Signature >> Signatures …
10. Click New and create a “Test” Signature.
11. Click into the Edit Signature Editor pane.
12. Press Ctrl-V to paste.
13. et Volia. The signature now shows the previously hidden borders.

I also tried copying a signature with a “no borders” table from Word into an Outlook email message and the borders started showing in Outlook when they were not visible in Word.

Microsoft 365 (Office) Updates

13-Jan-2026: The Microsoft 365 (Office) update, Outlook Version 2512 (Build 19350.20138 Click-to-Run) does not fix the issue.

14-Jan-2026: The Microsoft 365 (Office) update, Outlook Version 2512 (Build 19350.20144 Click-to-Run) does not fix the issue.

21-Jan-2026: Microsoft support has acknowledged the issue and posted it as a known issue: Classic Outlook adds table borders to signatures after updating to Version 2512.

22-Jan-2026: The Microsoft 365 (Office) update, Outlook Version 2601 (Build 19628.20106 Click-to-Run) does not fix the issue.

25-Jan-2026: The Microsoft 365 (Office) update, Outlook Version 2601 (Build 19628.20132 Click-to-Run) does not fix the issue.

29-Jan-2026: The Microsoft 365 (Office) update, Outlook Version 2601 (Build 19628.20150 Click-to-Run) does not fix the issue.

04-Feb-2026: The Microsoft 365 (Office) update, Outlook Version 2601 (Build 19628.20166 Click-to-Run) does finally fix the issue. The table is still showing as “class=MsoTableGrid” in the signature’s HTML file, but the border is staying hidden. 😊

More Information

For more information see the following articles and posts:

• Forum Thread: Email Signature has just added borders to a table that did not have them as recently as 23/12/2025
• Learn Thread: Outlook signature now has borders (table)
• #MSOffice Changing the Aptos font back to Calibri in Microsoft Outlook
• Microsoft 365 Apps for Windows: Release notes for Current Channel
• Microsoft Support: Classic Outlook adds table borders to signatures after updating to Version 2512

This Outlook bug is in addition to the fact that Word, Excel, PowerPoint and OneNote now pause for about 25 seconds after being opened showing “(Not Responding)” before they are actually usable since the 16-Dec-2025 update, AND that everyone using Microsoft Teams to store files now cannot find the “Files” menu option as it was unexpectedly renamed to “Shared”. Looks like enough people have had this issue that a pop up has been added. It just showed up:

Keep up the great work… ☹️

David

12-Jan-2026: Updated with Workaround 3 thanks to Piet Moen.
13-Jan-2026: Updated with testing results for new version.
14-Jan-2026: Updated with testing results for new version and added repro steps.
16-Jan-2026: Added Microsoft Learn Forum Thread, possible solution method.
19-Jan-2026: Added comments about the White Border method fails for Dark Mode.
21-Jan-2026: Added link to known issue article from Microsoft. Also fixed workaround solution 4 and added workaround solution 5.
22-Jan-2026: Updated with testing results for new version. No fix yet, be we do have workarounds.
23-Jan-2025: Updated solution 4 with note about changing borders when editing the HTML file.
25-Jan-2026: Updated with testing results for new version.
27-Jan-2026: Updated solution 4 with an additional border type.
29-Jan-2026: Updated with script to automate workaround 4 table type change and testing results for new version.
01-Feb-2026: Added simple solution as Workaround 6.
04-Feb-2026: Updated with testing results for new version. It is finally fixed.

This article was originally posted on http://www.winthropdc.com/blog.