Digital signatures on e-mails; Outlook converting signed message into attachment :(

[Cerulean]

Greetings,

A few days ago someone has e-mailed me and their e-mail in my inbox appeared with a red ribbon next to it. When I open it or preview it, I can read what they wrote and see that they also have a signature.asc attachment.

Our e-mail environment is an in-house hosted Microsoft Exchange setup. With instructions from Microsoft at https://office.microsoft.com/en-us/...ges-with-a-digital-signature-HP001230539.aspx I created a digital signature using Comodo. When I send a signed message, Outlook converts the message I wrote into an attachment, attaches it to a new e-mail with a blank body but with the Subject I wrote, and sends it to intended recipients.

How can I get it to sign messages without converting the whole e-mail message into an attachment and forcing recipients to open the attachment to read my message?

I want to know how, with Outlook 2010/2013 on Exchange, I can send messages that too have a signature.asc and receive the ribbon mark.