LG enV VX-9900

I have been trying to send a ring tone to my sons phone. I used the same method as I have always used (thanks to the info provided on this site) but everytime I send the file it gets returned as undeliverable. Sometimes it doesn't give a reason. Others say it has F**K in the body or header which it does not. I have tried other email addresses to send them from with no change. Could Verizon be onto this method and be trying to squash it?
Thanks,
Dave