Use this glossary to understand the results from Mimecast SPF Record Check
SPF record existence
Logically we require a SPF record in your DNS so we can validate it.
Multiple SPF records in DNS
You can only have 1 SPF record in DNS for each SPF version. If you publish multiple SPF records (v=spf1), this will invalidate your SPF record. Therefore, you should always update your SPF record rather than entering a new record beside the existing one.
When using SPF, you can only perform 10 (nested) DNS lookups.
PTR Mechanism Used
We recommend not to use PTR as this is a deprecated mechanism and several senders may (completely) ignore your SPF record if you use this.The function of a PTR record is the opposite of an A record. Instead of resolving a domain name to an IP address, the PTR record resolves an IP address to a domain name. The PTR mechanism validates if the DNS reverse-mapping for an <ip> exists and if it’s able to point to a domain name within a particular domain. The PTR mechanism is slow and not as reliable in comparison with other mechanisms in case of DNS errors therefore we strongly recommend to not use the PTR mechanism.
Unknown Parts Found:
We have detected content which is not in the SPF specification.
+All Mechanism Used
If you use the mechanism ‘all’ with a “+” qualifier this means you essentially allow anybody to send email on your behalf. The record will first try to match the sending source to another mechanism. If this fails, the default behaviour is to still allow this source. Therefore, this setup is discouraged.
Our SPF record checker will try to validate SPF macro’s you use. Using some example data, we will give examples of the lookups receivers may perform based on your macro setup.
Record Termination Missing
An SPF record should always have a ‘default’ fall back mechanism. This can either be an ‘all’ mechanism or a ‘redirect’ modifier. We check if you end your SPF record with either of these.
Multiple Fall back Scenarios
A SPF record should have 1 fall-back scenario. You have defined multiple.
DNS Type “SPF” Used
You have published your SPF record in a DNS type SPF. This DNS type ‘SPF’ (/99) was introduced in RFC 4408 in 2006. However, this type became obsolete following RFC 7208 which states: SPF records MUST be published as a DNS TXT (type 16) Resource Record (RR)
You used uppercase characters in your SPF record. Although it is not a requirement, it is a best practice to publish your SPF records in lowercase.
After running your SPF record through all these checks, you can safely update your SPF record in your DNS!