Stop Outlook 365 from adding javascript to emails

Question

I've recently noticed that Outlook 365 has been adding JS to emails containing images. How do we disable this feature as I'm concerned this will greatly affect email deliverability.

Here's a pastebin with the JavaScript code, which I can confirm is not within my signature HTML file and can only be found when viewing the source of a delivered email: https://pastebin.com/ALqW0Yww

Others have reported it here https://www.reddit.com/r/techsupport/comments/16ch8l2/outlook\_adds\_javascript\_if\_an\_image\_or\_form\_is/

And here https://stackoverflow.com/questions/76977870/microsoft-outlook-auto-added-javascript-in-e-mail-signature

Answer 1

If you are in the Current channel, check for updates then restart Outlook and Word - even of no updates were found. (This may be a silent update.) It can take hours before it is available to you, so if it's not fixed on the first try, wait 6 hours and try again.

It was not fixed in the 2 insider builds.

Answer 2

The product team repro'ed it and is investigating. They know which feature caused it - I don't have an ETA for a fix. Thanks.

Many thanks for investigating, glad to hear a fix is being looked into, thank you!

Answer 3

I was able to repro it on messages sent from Outlook desktop and will ask my contacts on the product team about it.

-- Diane

Answer 4

Hello,

Just to confirm, I'm not using webmail, I am using the desktop Outlook, specifically Version 2308 (Build 16731.20170 Click-to-run).

I have run some more tests using two different accounts on my Outlook:

Test 1- Sent using my personal outlook.com account, no signature, one inline image in the message body. JavaScript was added in by Outlook.

Test 2 - Sent using my personal outlook.com account, no signature, no inline images, just the word "test". NO JavaScript present in the message source.

Test 3 - Sent using my business Google Workspace account, with signature that contains an image. JavaScript was added in by Outlook.

Test 4 - Sent using my business Google Workspace account, no signature, just the word "Test". NO JavaScript added.

It seems it's a feature in a recent/2023 release of Outlook as this was not an issue in December 2022 when I had last checked our email delivarbility, so if you are to run tests, please do so using the very latest version of Outlook 365 desktop.

Many thanks!

Answer 5

Hi, I'm Diane and I'm happy to help you today.

Are you using Outlook on the web or Outlook desktop software to send the message?

Are you receiving it in Outlook on the web or Outlook desktop software?

I'm not seeing the script in messages I send - how complicated is your signature? Did you create it yourself or use a website that creates a signature and paste it in?

If you have any questions, please don't hesitate to ask.

-- Diane

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