Question: Which channel should I choose for a segment?

You should choose all the channels that you want as data sources for this particular segment.

Newsletter delivery data, message opens, clicks, list joins and unsubscriptions are in LianaMailer channel.

LianaAutomation has all the data about all the automations that a certain contact has been added to.

Contact details can usually be found in either LianaMailer channel or a channel that has been linked with the customer's own data system.