Giving up control and selling the sales team represent some of the biggest challenges to implementing machine learning into email marketing. Or so say Jennifer Muse, Senior Director, Email Product Marketing, Lifescript and Jon Weiss, Director, Email Marketing Operations, Sirius XM Radio Inc.to moderator Chris Marriott, Senior Vice President of Strategic Partnerships, CertainSource at last week's Email Insider Summit.

Email is becoming one of the best persistent identifiers because Gmail is so "sticky," says Phil Davis, Chief Business Officer, TowerData, at last week's Email Insider Summit on Amelia Island.

Metaphors were flying at the Email Insider Summit panel on cross-channel marketing last week on Amelia Island. Don't "boil the ocean" or "eat an elephant" advised our panel. It is easy to get overwhelmed by the enormity of the challenge and set ambitions too high.

Cross-channel marketing is not just about the big plan and the tech. It requires internal buy-in on multiple levels. Our Email Insider Summit panel on cross channel last week at Amelia Island addressed the issue.

It is not just the channels that are siloed. It is the data, too. VISA's Mary Grundy outlines just how deep the change needs to be among brands to realize the holistic consumer view.

It depends, of course. Every brand has to measure a number of parameters before determining when a user is really inactive. Our panel on "Searching for the Next New Thing" at the Email Insider Summit last week wondered aloud, when does inactivity mean your email approach isn't working?

Jealous of Uber's wealth of detailed user data? According to their eCRM Manager Wayne Miller, even this master of data can get overwhelmed by it all and finds it best to start with small actionable uses of data points. Warner Music Group's Itay Rahat, Director of CRM Product offers some example of the little things that work.