What is SPF flattening and how does it help?

SPF flattening replaces dynamic lookups with static IP addresses:

Before flattening:

v=spf1 include:_spf.google.com include:sendgrid.net ~all

(Multiple lookups from each include)

After flattening:

v=spf1 ip4:209.85.128.0/17 ip4:74.125.0.0/16 ... ~all

(Zero lookups, direct IP matching)

Benefits:

Reduces or eliminates lookup count

Avoids permerror from exceeding limits

Trade-offs:

Must update when source IPs change

Manual flattening is error-prone

Record becomes much longer

Automated flattening services solve the maintenance problem.

Copy the addresses from referenced documents into your own. No cross-referencing needed, but copies must stay current.