Office 365 “Reply all is not allowed on this item” with S/MIME e-mail.

Suddenly Microsoft have invented a problem for me (and everyone).

All e-mail I send is Digitally (S/MIME) signed. This has worked absolutely fine for almost every single recipient except for “Windows Live Mail” (the application).

But within the last few weeks Microsoft seem to have invented a problem for S/MIME e-mail sent to Office 365 recipients.

They can open the e-mail and see who sent it, the subject and the content of the message. What they are now unable to do is open any attachments (they can’t even see them) and they are also unable to Reply, Reply All or Forward the message!

cant reply office 365.png

They are greeted with a message box saying “Reply all is not allowed on this item” or “Reply is not allowed on this item”.

Very, very frustrating.

What is more worrying is I’m also unable to view the own attachments I’ve sent! If I log into OWA and go to sent items it has the attachment paper clip in the message list but when I click on a message the attachment isn’t visible.


Time for some testing. I created a brand new account on my Office 365 tenant and then sent it two messages. One digitally signed and the other not digitally signed.


main owa cant reply to digitally signed missing attachment
Full OWA: Can’t reply and can’t see the attachment on a Digitally Signed message.


main owa can reply to non digitally signed missing attachment
Full OWA: Can reply and can view attachment on a non-Digitally Signed message.


old light owa can reply and shows attachment on digitally signed message
Lite OWA: Can reply and can view attachment on a non-Digitally Signed message.

old light owa can reply to digitally signed message.png
Light OWA: Can reply to the signed message, unlike the full OWA.

So.. time to spend hours on the phone with Microsoft :\

Has anyone else noticed this problem?

It looks like it might have been a problem at some time in the past too but can’t have been happening recently as my contacts have been able to actually view my invoices (and pay them) until recently.

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9 Responses to Office 365 “Reply all is not allowed on this item” with S/MIME e-mail.

  1. Bob says:

    I have the very same problem for the last month or so. Can’t see attachments on digitally signed email, or reply to them. Is there a fix to this?

  2. Not that I’ve found. As a sender who uses O365 – I’ve had to just turn off signed messages :( [I wasn’t remembering to un-sign messages with attachments].

    I did try calling Microsoft but the eternal hold music won the battle and I had better things to be doing.

  3. Bob says:

    sir- my problem is I get digitally signed email….these are the ones I can’t reply to. Is there a way for me to negate O365 from identifying these as digitally signed, so it won’t hide the attachments? Thank you for your expertise….I’m lost with any of this stuff!

  4. Andrew Hydle says:

    Any luck with this? I was just looking at setting up SMIME for my org but this is kind of a game killer for me. Was about to file a ticket but that is a nightmare…

  5. I’ve not had the energy or time to call MS over this :< One day maybe.

  6. Rafael says:

    I have exactly the same problem, in IE you can install the Microsoft extension and it works, but in Chrome or Firefox no way.
    Here is the reply from microsoft:
    Your question on Microsoft Community has received a reply from Rick Xu MSFT Support.
    Title: Digital Signature S/MIME

    Hi Ramiz,

    Currently S/MIME is unsupported for Firefox, Opera, or Chrome. S/MIME is supported by Internet Explorer 9 and above, Exchange ActiveSync(EAS) clients and Outlo0k 2010 or higher.


  7. What is more annoying is I’m pretty sure it used to work until a few months ago. It would warn the recipient that the signature couldn’t be checked but would still allow them to view the attachment and reply to the message. Something then changed to prevent both of these being possible without the S/MIME plugin :\

    Very frustrating.

  8. Steve Kurak says:

    I have the same problem with not being able to view attachments that I put into a message. I have to save the message to drafts then open it up again to “continue Working” to se the attachments.

    I am unable to respond to signed messages, sent to an account that has no certificate associated with it. My error sys unable to find S/MIME certificate. I do not have send digitally signed turned on and I ran the Outlook 365 S/MIME utility. No Joy, so I have to respond to every digitally signed message I receive with a “fresh” message response/. How annoying

  9. Renay S. says:

    Here’s how I was able to remedy this problem:

    Click on the email and you’ll see this at the top “S/MIME isn’t supported in this view. To view this message in a new window, click here”

    Click on “click here”

    A new window will appear and from there you’ll be able to reply/reply all.

    Hope this helps!

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