Need to include actual attachment file with correspondence email


I have a situation where occasionally RT correspondence will be sent to
parties who do not have access to RT. This is particularly troublesome
for correspondence that refers to attachments within RT, as these users
would be unable to authenticate to view the attachment. For policy
reasons, we cannot give them access to RT, so as a workaround, I am
trying to figure out how to include the attachment itself within the
correspondence email. Thus far, I have discovered how to include links
to attachments within emails:

This works fine for people who have access to RT, but fails for those
who do not. I have been unable to find any information on how to include
the actual attachment within the email, which would solve the problem
for the non-RT users.

Any pointers to information on how to do this? I’m currently running RT