You can write a message to your recipients on the iPhone app by accessing the Recipients screen. To get there from the home screen, tap "Post Box" at the bottom of your screen, next tap "sent" from the menu on the left, then tap on the appropriate card image.
Next tap "Event" or "Recipients" (this depends on whether or not you're collecting RSVPs) to get back to your recipient list. Finally, tap "Write a message" to access the messaging menu.
You can write a message to your guests on RSVP events on the iPad app. From the home screen, tap the set of three lines at the top left corner of the screen, then tap "Post Box" when the menu appears. Next, tap "Sent" and find your card in the list.
Tap on the appropriate card image to open it. Once the card loads, tap the middle 'Event' tab at the top of the screen and then tap the speech bubble to access the messaging menu.
Can I send an auto reminder?
Unfortunately at this time the iOS apps do not have an option for you to schedule an auto reminder for your guests, but we're hoping to have it available in the future. If you need to schedule a message to send at a later time, you can do so by accessing your Tracking page from a desktop browser.