The billing model for AutoSPF is based on consumption. The more the service is used to higher your bill but the lower the cost per query.
But what is a query?
AutoSPF uses commercial DNS providers (Cloudflare etc.) to host the DNS records for your flattened record. An example of this record is _s00000021.autospf.email. The record has two parts
Domain Name: autospf.email
Host Record: _s00000021
The way that our system tracks consumption is to pull reports from the DNS provider on the number of queries that each individual host record receives. The number of queries to this record is how we track consumption.
Does one email mean one query?
No. Queries to the host records are typically cached on the receiving server. And as long as the record is cached they will not query the authoritative source (our DNS). If more emails are received by this source and the lookup is cached on their side, these messages are not tracked in our system.
A practical example in Business to Consumer emailing.
If 1000 messages are send to gmail, we have seen query numbers as low as 70 for them all to be delivered.
A practical example in Business to Business emailing.
If 1000 messages are send to 1000 unique email addresses you would expect 1000 queries. However because a large percentage of these customer domains are going to be on the larger email hosting providers (Google, Office 365) the number of queries again are going to be limited. Theoretically it could be 1000, but it is more than likely less than 250 queries.