Exact Target in combination with CoTweet has released a pretty interesting research series about the interdependencies of email, Facebook and Twitter.

One of the key insights form the study for me is that while email, Facebook and Twitter compete with one another for marketing budgets, consumers really expect brands to interact with them across all three channels.

That said, it's interesting to see that Twitter consistently scores higher than email and Facebook. For example, over 30% of Twitter followers are more likely to purchase or recommending a brand after becoming a follower whereas email and Facebook score more around the 20% mark.

However, I'm not sure I agree with the channel breakdown by reach, retention and acquisition that the study suggests below, the results may support this interpretation but the real world seems a little more difficult.

Download the full research report series from the official Exact Target & CoTweet website.