I create a comment (this one for example). the comment as you can see have mentions

after publish, I create a "Notify blob" that I then push to the Notify server I have setup in my desktop app and also to all the nodes I'm connected connected with

Each node knows what to do with this Notify blobs. some can do something (increment the notification number if you are one of the accounts mentioned in the comment) and som does nothing

When the Notify server receives the Notify Blob, then reads the content of the comment and trigger all the emails sent that needs to be sent.

If you are offline, no worries because you will have the Notify blob and when back online you can still send it to all your nodes including the notify server