Can someone tell me the legend/format of the pop3d log entries?

I see these entries in the logs across serveral servers.

Mar 5 10:56:25 cpanel4 pop3d: LOGOUT, user=tammi@local.com, ip=[::ffff:760.13.112.418], port=[37254], top=0, retr=0, rcvd=12, sent=38, time=0

I want to know what the retr rcvd sent mean and from what point of view?

I assume it's bytes sent and received from the server's point of view, but I see a number in rcvd but not retr, so they must mean something different.

Thanks,
Chuck