There are two common approaches for leveraging partnerships to grow your e-mail list: third-party partner mailings and co-registration. But I wouldn't run at either opportunity blindly. Growing your list organically will always produce the most qualified audience.
Co-registration allows for you to include an opt-in to your e-mail program when a person is subscribing to the partner's. While the opt-in is explicit, the actual act of subscribing may be quickly forgotten depending on whether the box is pre-checked or not. Another challenge is that since the subscription did not come from your site, there may be some delay in getting the data to you—which could prevent you from sending a timely welcome message directly from your brand. Co-registration can be a very successful acquisition method if partners are carefully chosen, but remain mindful of the data challenges that may be associated with this method of acquisition.
Leveraging partners can be a safe way to add new addresses to your promotional e-mail programs. Just choose the right partner with the right audience, build the right strategy first and then let it takes its course.
Kara Trivunovic is senior director of strategic services at StrongMail Systems (www.strongmail.com), a provider of e-mail marketing solutions.