DNS

DNS

DNS Lookups in SPF

DNS lookups are the queries receivers perform to fetch SPF policies and resolve hostnames to IP addresses during authentication.

Intermediate 6 min read

DNS

MX Records and SPF

The SPF mx mechanism authorizes IP addresses of the domain's MX hosts, linking inbound and outbound mail DNS in specific scenarios.

Intermediate 6 min read

DNS

DNS Propagation and SPF

DNS propagation delays can cause temporary SPF failures after you publish or update TXT records.

Beginner 5 min read

DNS

TXT Records for SPF

SPF policies are published as DNS TXT records at the domain or designated subdomain used in the envelope sender.

Beginner 5 min read

DNS

SPF DNS Lookups Explained

Every include, a, mx, ptr, and exists mechanism in SPF triggers DNS lookups that receiving servers must perform during evaluation.

Intermediate 7 min read

DNS

Recursive SPF Resolution

Recursive SPF resolution is the process receivers use to walk includes and nested policies until a match or terminal mechanism is reached.

Advanced 8 min read

DNS

Nested SPF Includes

Nested includes occur when an SPF include points to another policy that contains additional includes, multiplying DNS lookup cost.

Intermediate 7 min read