To be accepted into Return Path's Certified IP whitelist, a sender's business model must meet certain requirements. This includes sending email only from dedicated IP addresses.
- Dedicated IP addresses are those used by a single sender or company.
- Shared IP addresses are dynamic IP addresses that can be used by thousands of senders.
You cannot share the use of Certified IP addresses for the IP whitelist, even with organizations you have a relationship with.
Mailbox providers base sending reputation off IP address traffic. Senders can only control their reputation and status in the IP Certification program by sending from dedicated IP addresses. The metrics that Certification monitors will not be accurate for a sender if other companies are also sending from the same IP address. For example, complaint rates will be representative of all senders using the IP address, rather than one sender.
Senders using shared IP addresses may apply for Return Path's Domain-based Certified Whitelist.