Port settings should be as follows:
Code:
zmprov -l ms server.domain.com zimbraPop3BindPort 110 zimbraPop3SSLBindPort 995 zimbraPop3ProxyBindPort 7110 zimbraPop3SSLProxyBindPort 7995 zimbraImapBindPort 143 zimbraImapSSLBindPort 993 zimbraImapProxyBindPort 7143 zimbraImapSSLProxyBindPort 7993
You can run that command (all on one line) and the proxy ports are (obviously) the 7xxx ports and should be allowed through your firewall.