Earlier you mentioned on Your DNS server and you list webmail with 2 address and internal and external.
Your external DNS, the one registrar controls, which looks like network solutions needs an entry for webmail.domain.com pointing to the 216 address your wife used to get in. You internal DNS server should only have the internal 10. ip address. Can you post a screen shot from your network solutions control panel with the DNS settings. Feel free to cover the IP addresses i just want to see the entreis there and make sure you ahve the right ones up.