1. What Are Data Response Codes?

The data response codes are a machine readable way for the IADB to provide email receiving sites that query the system with information, or "data points", about the email sender in question.

For example, a data response to a query may reveal that the email sender in question is listed in the IADB, publishes an SPF record, and builds their mailing lists by double opt-in. Or it may tell the querier that the only information available about the sender is that they are listed in IADB, or that they are not listed in IADB at all.

2. What Are the Data Response Codes, and What Do They Mean?

The data response codes are all in the 127.x.y.z range.

The "x" and "y" value generally indicate the "what" of the data, i.e. what the information provided is, while the "z" value generally indicates the "how much", or the "if" in the case of a simple "yes/no" data return.

For example, 127.0.255.z is reserved for information about whether the listing is a vouched* listing. In this case ISIPP provides information that a listing is a vouched listing, or that it is not, and so the "z" value indicates simply "yes" or "no", with "255" being "yes", and "0" being "no". (*A vouched listing means that you are either personally known to ISIPP or a referring group, or that your reference and background check and mailing practices demonstrate that you are someone to whom we would refer others for services.)

Another example would be the 127.3.3.z range, which is the level of opt-in for the sender's mailing lists as reported by the senders themselves (there is another range for externally verified opt-in levels). Again, the "z" value indicates "how much", with 127.3.3.1 indicating an opt-out policy, 127.3.3.10 indicating that all of the sender's mailing lists are confirmed opt-in, and values in between indicating an intermediate opt-in level.

Note that there are exceptions to the "z" = "how much" or "yes/no". In ranges from 127.2.128.z through 127.2.255.z, the "y" indicates a category, and the "z" indicates an affirmative for a subcategory. For example, 127.2.255.z is reserved for information about external authentication systems in which the listee may participate, such as SPF or Ironport's Bonded Sender. A score of 127.2.255.1 indicates that the sender publishes an SPF record, a score of 127.2.255.12 indicates that the sender is listed with Ironport's Bonded Sender program.

Confused? It's ok, these codes are meant for computers to read, but if you really need to know exactly what a given code means, you can look it up on our code list.

3. How Did You Come Up with the Data Response Codes?

ISIPP worked closely with both leading spam filters and ISPs to develop the data response codes. They are based on what ISPs and spam filters need in terms of both data format, and data content.