Thank you for writing to Aspose support team.
We have investigated these two issues at our end and were able to reproduce the same at our end using the latest version of Aspose.Email for .NET 5.4.0. Both the issues have been reported to our Product team as per the following details. We’ll notify you here as soon as there is some information or a fix version available in this regard.
EMAILNET-34822: MSG to MHTML: Text missing from message body
EMAILNET-34823: MSG to MHTML: Encoding issue in output