Apostrophe rendered as "'" in emails, on Outlook

Hi everyone. I use ghost to email thousands of members. One of them who uses Outlook (native client on windows) sees “’” wherever a simple apostrophe should be (for example “it’s” instead to “it’s”.

Has anyone else experienced the same problem? Is it something to do with how Ghost renders HTML or something beyond my control?

Are you writing posts in Ghost? or perhaps pasting from another editor?

I wrote these posts in Ghost. I may have copy-pasted from within the article while editing but nothing external.
Also the “&apos” appeared even in text that was placed within markup/quote sections.

Not sure in that case, haven’t heard anyone else report this so far!

It looks like it only happens in Outlook. Happened on multiple posts to multiple users, and to all apostrophes, so not a matter of copy-pasting from a different source.