As a simple test, we open a msg file and then save it without any change. .msg file size before change is 15 kb and once we save it with this component size gets increased to 57 kb. this is consistent across multiple emails.
Here is the code that we are using.
MailMessage msg = MailMessage.Load(MSGFilePath, MailMessageLoadOptions.DefaultMsg);
msg.Save(System.IO.Path.ChangeExtension(MSGFilePath, "_Converted.msg"), Aspose.Email.Mail.SaveOptions.DefaultMsgUnicode);
I've attached the original and modified .msg file.
Thanks,
Himal