On a classic Simpsons episode, Homer was dismayed to discover the reception for his Everything Is Okay! alarm was less than favourable. It seems people don’t like being loudly shouted at unless one has something urgent and important (not the same) to attend to.
This isn’t about iOS notification spam this time however, it’s the otherwise excellent Inverse SOGo Connector plugin for Thunderbird. With it, you can sync your contacts with third party DAV services, such as Fastmail.
Set it to perform periodic sync however, and you'll be notified every fifteen minutes of every operation, even if it didn't do anything.
These popups have no reason to exist. Fortunately, these can be disabled. In the address book, right click your synced account, click Properties, and tick "Notify only if data syncronised".
Update: They persist even with this setting checked, darn. Untick all notifications, and you’ll be fine. Realistically, unless you're a socialite or in high pressure sales and are constantly getting new contacts, you won't need these notifications anyway.
Update Again: I knew I remembered the name Sogo from somewhere; they’re a Japanese department store chain that had a branch in The Paragon in Singapore when I was growing up. It’s a Metro, now.