It's the subject that draws the attention to your message, and subjects can also contain very helpful information about the message contents (for instance "Order confirmation #781265" or "Your invoice for July"). Some sources have limited options in formatting subjects and you might even want to toy around a bit, trying different more inviting subject lines later on. This FlowStep rewrites the message subject (you can also re-use the original subject in your new one, which is the default value). You can also use all template functions in here, so dynamic subjects are possible as well.
