For a recent application I developed, I used a series of 3 automated emails post sign-up. The first was sent right after signing up, with a "personalized" welcome that came directly from my email address. The second came 5 days into the trial period with suggested activities to try within the application, again from my email address. The third was sent 15 days into the trial and included links to the help and support site, along with links to tutorial videos for advanced activities. The third email was sent from our support team email address. Each message included the option to stop receiving general inquiry emails.