Email signature not being stripped out when user write new topic or reply to a topic

Markdown uses a bunch of hyphens for a horizontal rule. We have messages that include meeting details below a horizontal rule. Is there an alternative that we can use to make a separator without causing trimming?

For example, an example incoming email might contain the following:


This is the content of an example email. It might contain meeting details. If this post were sent via email, then this part - and everything after it - would be trimmed.


Thanks!