Thank you for writing to Aspsose Support team.
It seems the issue is similar to the already logged issue EMAILNET-35175 at our end that is caused due to the presence of Reply-To header. It has been fixed and will be available in the upcoming release of Aspose.Email API. However, please share your sample file with us so that we can check it again at our end and report it to our Product team if it is a different problem than the already logged.
The release will be available at the end of next week. We’ll inform you here as the fix version is available for download.