I have tried several times to send an attachment using simple mail. I have tried sending Word documents and PDF documents and neither will open when the recipient receives them. When I try to send an email with an attachment to my hotmail account, which doesn't go through simple mail, I receive the following when I try to open the attachment.

Server not found

Firefox can't find the server at 1351311760981%40simplemail.

Check the address for typing errors such as
ww.example.com instead of
www.example.com
If you are unable to load any pages, check your computer's network
connection.
If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web.
______________
Or else I get an "The address is not valid" message when trying to open the attachment.

Why can't the attachments be opened that are sent through simple mail? I use my Charter.net email address with simple mail and I can log onto their website and send attachments with no problems, so I know it has something to do with simple mail. Please help.