What's the best approach: real time email notifications or digest emails at regular intervals?

Question

I have a Q/A site that deals with my area of medical practice. I'm a doctor and a programmer. Users can do the typical things like follow threads and other users.

I don't want to spam users all the time with email updates on activities of followed users but I want to keep things 'circulating'. It hasn't launched yet so I face the obvious issues of almost no users to begin with.

What's the best approach - email users in real time when relevant activity occurs or send out periodic emails containing all the latest activity since the last email (I suspect this option will be difficult to program)

Answer 1

The best course is to provide multiple options to the user.

Generally you'll want to provide at minimum, the following three options:

• Send the notification of activity immediately
• Send a summary of activity that occurred for a given time period (1 day, 1 week, etc. - the period should reflect the expected user goals for your website)
• Never send any notifications

For example, Trello does their email notifications in this manner:

Answer 2

Although the answers you've been given so far are correct, I'd argue that giving the user too many options is a bad thing as well.

Is having three options really necessary? Would two work? If so, use the one with the least amount of options. I'd say give them an option of "keep me updated" or "never". This way, you're doing two things.

1. Your easing the decision making process
2. You're not overloading your server by constantly sending emails. Simply batch process them every so often during the day

Answer 3

As grover5 says, give the user choice. That'll probably end up as the best solution in terms of UX as the user can customise her own experience down to how she likes it. That means positive feedback and more users for you.

However, if for some reason you can't provide this option, it depends on the number of users and level of activity you have. As you say, spamming users with emails is annoying and counter-productive. As a general rule from a user's point of view, I wouldn't want any more than ~5 emails a day from a site, at absolute maximum, though even that might get annoying. Opinion on this will be divided though. The best advice I can give here is to do testing on yourself. Sign yourself up for all the emails you send; if they annoy you, they'll annoy your users and you should cut them down.

So, to summarise - if your users are going to get any more than X (insert daily maximum) emails per day, you should be sending daily/weekly digests.