Co-registration (or co-reg, as it is commonly known) is rapidly gaining ground as a media tactic. In the age of CAN-SPAM, and with an increased understanding in the market about the importance of user permission for effective email communication, co-reg is an attractive option for building a house list.

Unfortunately, few marketers treat co-reg as a distinct tactic, and instead simply apply the business rules of their standard online media buys. This can be a costly mistake.

This article discusses the most important issues to consider when crafting an insertion order (IO) for a co-reg buy.

The Obvious Stuff

Besides the buy value, payment terms and start and end dates, here are the terms, specific to co-reg, that need to be included in your IO.

All Data Must Be Opt-in

Opt-out data does enormous damage to brands and should never be used by legitimate marketers. An IO needs to state explicitly that the buy is for opt-in data only. Since many vendors use the term loosely, you need to define "opt-in" carefully. For me, an opt-in name is of a user who expressly requests to receive a specific email communication from a specific brand by taking some form of affirmative action to request such email communication.

Specify Data Fields

Specify exactly what data fields need to be supplied for each opt-in record, and make it clear that records not containing these fields will be invalid. Most co-reg publishers collect first name, last name, email address, ZIP, and country as a matter of course. But it is best to specify these (as well as any additional fields you require) in the IO. Also be sure to specify the required data transfer mechanism and file format, for example daily .csv files via email or direct data posts.

Collect Proof of Opt-in

It is best practice to collect data proving that a specific user did, in fact, opt in. To protect against potential abuse complaints, you need to collect time and date stamp ("when" the user opted in), IP address (from where the user opted in) and source site (the Web site where the user opted in). You should never buy or accept data from co-reg networks or brokers that cannot or will not provide these data fields.

The Battleground

Now for the difficult (but really important) stuff.

the Take-Down

The most contentious aspect of any co-reg media buy is the take-down (also known as the rejection rate or scrub rate), or the number of delivered records the advertiser does not pay for based on agreed criteria. There is no industry standard defining valid and invalid data, so be sure to list all the criteria clearly in your IO and ensure that these criteria are mutually agreed on during the media buy.

Examples of take-down criteria that make a record invalid may include email addresses containing invalid characters or in an invalid format, hard bounces (properly formatted email address not recognized by domain server when mailed immediately after opt-in), email addresses containing profanity, duplicated records and records that already exist in the advertiser's database (already subscribed users).

Controlling Distribution

It is vital that you know exactly where your opt-in offers will be running and that you audit and approve each site's opt-in process. This might seem like a massive chore, but if you skip this step your offer may appear on some dubious sites, with the result that you receive tons of low-quality data.

If a co-reg "network" refuses to disclose the sites where they will run your offer, take your money elsewhere. The networks with strong publisher relationships and ethical business practices will have no problem giving you site lists. Make sure that the approved site list is included in the IO and that you include a term that specifies that your offer will not run on any sites containing content unacceptable to you (e.g., pornography, violence, racism, sexism).

Protecting Your Data

Most co-reg publishers and networks are in "the data business"; in other words, they generate and sell data for a living. For that reason, you need to be very clear about data ownership and privacy.

The generic demographic data collected as part of a site's registration process can clearly be used by the publisher as it sees fit. However, additional data that is collected as part of a specific advertiser's opt-in offer (including the fact that the user opted in to that offer) is the property of that advertiser and must not be stored, analyzed, sold or used for any purpose other than transfer to the advertiser.

A Final Word

Co-reg is a very effective way of building high-quality house lists, but it can also be a minefield.

Make sure you work through the above issues with your co-reg publishers or networks, and include the relevant terms in your IOs. Doing so will not only ensure healthy relationships with co-reg publishers but also protect you and your clients from possible legal risk.

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Stephan Pretorius founded Acceleration in 1999 and is currently responsible for product development and client strategy. For more information, visit