Under Return Path's Certification program:
- Measurable volume means 200 email messages (100 to Yahoo! and 100 to Microsoft) are sent in a 30-day period from each Certified IP address. The number of IP addresses senders own and have Certified should also be relative to the volume they send.
- Consistent volume means that IP addresses have been used consistently for at least 90 days.
Return Path can only effectively monitor IP addresses or domains sending measurable volume. Also, IP addresses and domains with zero sending volume present security issues.
IP addresses or domains without measurable volume will be suspended after 30 days and removed from the Certification program after 60 days.