Using W/ a Proxy Server


I'm having trouble using Mail while connected to a PROXY server @ work. I am unable to connect to any of my three mail accounts [either incoming or outgoing]. I have all appropriate settings, IPs, and passwords enabled in System Prefs [i am succesfully able to connect to the internet and my keychain seems to be doing it's job w/ all other internet apps, such as Dashboard, HelpViewer, etc.]

In the SysPrefs 'Network' pane, under the Proxies Dialog i have:
Configure Proxies: Manually

FTP Proxy: checked
WebProxy (HTTP): checked
SecureWebProxy (HTTPS): checked
StreamingProxy (RTSP): checked
SOCKS Proxy: unchecked
GopherProxy: unchecked
AutomaticProxy Configuration: unchecked

FTP ProxyServer:
i've entered our server's IP
w/ ports :8080

ProxyServerRequiresPassword: checked
i've clicked 'set password' and entered the username and password

ExcludeSimpleHostnames: unchecked
UsePassiveFTP Mode (PASV): checked

I am unsure of what the 'BypassProxySettingsForTheseHosts&Domains' really does. Will it help to add my incoming and outgoing mail servers to this field?

Also, is there a preference in Mail [such as 'server settings'] under the 'accounts' prefs that will allow my proxy server to access these mail servers, or is it something that I have to change on the server itself?

I appreciate your help, thank you

chase luikart