Linda,
It isn't clear from your posts as to what is on Yahoo. It could be that there are actually 150 messages that contained eml files within them and another transfer would just do the same thing.
eml files are a format for saving emails to files. You can view eml files with a text editor to see the text in the email. Your description of emails within messages is a legitimate way to send an email within another email message.
--
Gerald
