Nothing else but the format should be checked and ANY kind of error should be properly communicated.
I had two situations recently that cost me a substantial amount of time and effort, due to f**ed up email handling and non-communication to the user.
Once I tried to sign up to Pinterest with my personal catch-all domain using the emai [email protected]. Only received random errors no matter what browser and IP I tried, had to contact 'support' (three levels of bots) to eventually find out that 'pinterest' is a reserved word because of which they would not accept my email.
Second situation in a hotel trying to connect to WiFi via a captive portal. Using email [email protected] (which I used to check in and was thus required to use in the portal) the page just refreshed again and again without throwing a user facing error. After significant back and forth at the reception I was educated that I was only allowed to use private / personal emails (meaning GMail). My own domain wasn't personal enough...
Both situations could have been rectified easily if proper errors would have been communicated.
I have no idea about any apple email addresses.
There’s definitely a big problem here with email, and I don’t know what the solution is.
As a web developer, I'm sure if you really want it one, you could create a quick throwaway email address using a small array of services.
Let's think about how strange this as far a bit, if you have a smartphone at all, you'll either have an email address provided by Apple or Google. Google. If you choose not to utilize either one of these, that's your choice.
At the same time, Sony has never been good with web technology, the PS4s online play has always been less feature-rich than Microsoft's offering.