The core of the configuration is available on the personal profile page. In my case the URL is https://ask.openstack.org/en/users/9/smaffulli/?sort=email_subscriptions: hit your username in the top navigation bar and then pick ‘subscriptions‘. The page will look like the screenshot below.
As of today Ask OpenStack gets around 10 new questions per day and the rate is increasing steadily. I highlighted the configuration that can help you prevent getting too many emails: select the frequency of the notifications want to get notifications first in the line “Entire forum (tag filtered)”. Then set the tag filter: I picked “only subscribed tags”. You can modify the tags you want to receive notifications from the form at the bottom of the page:
Tags are added by the person asking the question and can be edited by anybody with karma higher than 100. On the same subscriptions page there is also a setting to receive notifications for questions asked in Chinese languages.
On Ask OpenStack home page there are also ways to customize the site further, hiding questions carrying ignored tags from the view or highlighting interesting ones