Does not work edit .msg in outlook

I’m editing the .msg file in Outlook, it’s not creating the email with the changes

I noticed that the htmlbody and htmltext properties do not change, the body property changes, but when sending the email the change is not sent

MailMessage mailMessage = client.FetchMessage(info.UniqueId);
MapiMessage mailOutlookMapiMessage = MapiMessage.FromMailMessage(mailMessage);

MailConversionOptions mailConversionOptions = new MailConversionOptions();
mailConversionOptions.PreserveEmbeddedMessageFormat = false;

MapiMessage MapiMessageAlterado = MapiMessage.FromFile(fileMessage);
MailMessage mailMessageAlterado = MapiMessageAlterado.ToMailMessage(mailConversionOptions);

string uid = client.AppendMessage(mailMessage);


Could you send us an msg file example before editing in the outlook and after editing?