What code are you using to send / save the message?
The code below is what I use and it seems to work fine.
Dim objDoc As Object
Dim objRichTextAttach As Object
Dim objRichTextItem As Object
Dim objAttachment As Object
Const NOTES_RECIPIENTS = ""
Const NOTES_REPORTS_ADMIN_USER = ""
Const NOTES_MAIL_FILE = "C:\Email.txt"
Set objDoc = mobjDB.CREATEDOCUMENT
Set objRichTextAttach = objDoc.CREATERICHTEXTITEM("File")
Set objRichTextItem = objDoc.CREATERICHTEXTITEM(objDoc, "Body")
Set objAttachment = objRichTextAttach.EMBEDOBJECT(1454, "", strFile)
'set up the email to be sent
objRichTextItem.AppendText strBody
objDoc.REPLACEITEMVALUE "SendTo", strSendTo
objDoc.REPLACEITEMVALUE "Subject", strSubject
objDoc.SaveMessageOnSend = True 'send E-mail
objDoc.SEND False 'false for do not attach a form
EMAIL_REPORT = True