Could it mail the size of the files Cap'n? Try checking them out on your ISPs webmail site. Don't know who you use, but it's usually mail.ispprovider.com, and you can use your password there and read your mail.
As Bobad says you may have a restriction somewhere in your mail rules, just need to keep picking away at it, till you find out the problem I'm afraid. What you need is a tame geek!
Giok