There is a proxy but you would have had to say 'yes' to an option during install. Anyway, check the following to see if the proxy is installed/running:
If it's in, then run this:
zmprov gs server.domain.com | grep zimbraServiceEnabled
zmprov gs server.domain.com | grep zimbraServiceInstalled
To reset the ports run the following (on one line):
zmprov ms server.domain.com -zimbraServiceEnabled imapproxy
then restart There's details of reducing RAM usage on this page: Making Zimbra run on minimal RAM - Zimbra :: Wiki FOr testing, however, your current 1GB would be OK with the full product (except proixy ) installed. The aim of the exercise is to reduce RAM usage but not to cripple Zimbra, too low RAM will induce performance problems and make it unreliable and unresponsive.
zmprov -l ms server.domain.com zimbraPop3BindPort 110 zimbraPop3SSLBindPort 995 zimbraPop3ProxyBindPort 7110 zimbraPop3SSLProxyBindPort 7995 zimbraImapBindPort 143 zimbraImapSSLBindPort 993 zimbraImapProxyBindPort 7143 zimbraImapSSLProxyBindPort 7993