Every customer or prospect interaction is an opportunity for a savvy marketer. It’s an opportunity to generate revenue, foster loyalty, win back a former customer or gather data. For an email marketer, acquiring the email address is crucial.

The challenge for capturing email addresses is that the biggest touch points are already covered — websites, call centers and web checkout processes are all optimized for email list growth. It’s time to think outside the box.

There are some opportunities that you may be ignoring or underutilizing for growing your database.

Take, for instance, your Facebook page. Prime property exists on your Facebook page to promote, among other things, your email program. The space on the left sidebar can easily be leveraged to succinctly highlight your email offerings. Check out the Facebook pages for Domino’s Pizza and Lands’ End to see their online marketing efforts

Consider your Twitter page. Very much like your Facebook page, the same left-rail real estate exists on your Twitter page. Use this area to cross-promote your email program. A URL and copy simply need to be created for the posted image. Don’t anticipate huge numbers overnight, but small, ever-increasing numbers over time at zero cost make Twitter cross-promotion an simple decision when looking to grow an email list any way possible.

Furthermore, promoting your email program in a way that highlights its unique aspects may be done in the body of the social communication tool itself. Clearly, it must fit within the strategy and be done sensibly, but keep an eye on user feedback for comments on the value of the program and leverage that content.

And let’s not forget your email message. When your email is forwarded, it’s because someone identified the content as being valuable to another. The recipient is apt to want to receive that content on a regular basis. Make it uncomplicated for recipients to sign up by including a link at the bottom that overtly says, “Want to sign up for our email program? Click here.” Take that person directly to the sign-up page.

Then there’s your mobile program. If you are running a mobile program or are currently building a strategy, don’t forget the constant data exchange that this channel enables. Sending an email address to a short code is a great way to leverage one channel’s strengths for building out another. As always, providing an enticement — sent via email — will help in conversion and help improve data quality.

Email list growth, for most companies, is an effort in small incremental gains over time rather than radical changes overnight. String together several small tactics, however, and the numbers can start to have a significant impact after a few months.