I Need some help understanding the Daily Mail Report, specifically "Most active senders" and "Most active recipients".

We're Running Zimbra OSS 4.0.2 on CentOS 4.4. Running behind a Cable/DSL router with no open ports. Zimbra communicates to the outside Internet via "Relay MTA for external delivery" set to our ISP's mail server for out bound mail and Fetchmail setup for inbound.

I am seeing addresses with foreign domains in both Most active senders and Most active recipients.

I assume "Senders" would be Zimbra accounts sending mail and "Recipients" would be Zimbra accounts receiving mail. Am I misunderstanding these terms, or do I have an open relay situation.

Please enlighten me.