The two most important factors that are considered in the volume metric are consistency and frequency. In order to not lose any points for volume, send mail on a more regular basis with a gradual increase in volume. ISPs are wary of IPs that are sending unpredictable mail streams and favor senders with consistent mailing patterns.
If you’re losing points due to start ‘warming’ an IP, this is expected behavior. ISPs are typically cautious of any new IP that has no sending behavior associated with it. If you have several new IPs, you may want to consider our IP Warming Service. Speak to your Account Manager for further details.