Parameter values can include ;'s if they are quoted. For example:
Content-Type: text/plain; param="value with a ; in it"
Since the parser splits on ;'s, this isn't properly handled.
This is closed but with version 0.4.4 we still have this issue.
Yeah, I have fixed this in newer libmime, see here but due to the lack of time I haven't been able to back port it to the older mimelib (see here) that the mailparser uses.