Best practice for out-of-app notifications for in-app messages?

Question

Platforms like Task Rabbit and Airbnb send users an email and/or text message when an in-app message is received.

What is best practice in terms of UX for how and when these out-of-app notifications (e.g. email / text message) are sent?

One strategy could be to simply send notifications every time a message is received in-app. But I wonder if that could bombard users who receive a flurry of quick notifications, especially if those notifications are via text message or email. A counter argument to that could be that many message and email clients tend to group together emails from the same sender nowadays, so the recipient may not feel bombarded at all.

I thought about more nuanced approaches, where out-of-app notifications are only sent if certain conditions are met. For example max 1 notification every 30 seconds. But I'm not sure if that's a good idea.

So in terms of medium, frequency, and any other considerations, what are best practices for notifying users of an in-app message?

Answer 1

Let the user choose which notifications they want to receive and how often. Some apps/sites allow users to receive a weekly summary email bundling all of their messages/notifications. Others will send sporadic nudge/reminder emails about messages after a few days.

In general, I would say you should assume your users don't care about your app as much as you think they care, and that these messages are more annoying than they are helpful. If they really cared, they would just go back into the app and keep hitting refresh.

Also, if these are important messages, they should appear as a notification on your phone from the app (iOS and Android both support these), and not as email anyway. Lots of "chat" type apps do this. If these aren't so important, consider just having a notification bubble on your app and let the user decide to open your app again if they really want to.

In terms of what frequency is best for the default notifications settings, you won't really know until you do some user testing with a smaller group and find the sweet spot. I would say it should be limited to at most one email per day, zero text messages since some people have to pay for text messages. All email messages should have an unsubscribe link so you don't get blacklisted as spam.