Steps to Reproduce:

• Create an pop mail connection, and wait to see your email, then get the id from the mail.
  For example: http://127.0.0.1:808/display/DSP/mail/*753669*
• Following this documentation.
• Create a new page and write in the WikiMarkup area [$753669] then save that.
• You'll see that's working fine.
• Upgrade to 4.1.7
• Try to edit that page, which we linked that email.
• You'll see that's noway to save that.

Workaround:

• There's no workaround for that.