Which amcrest camera did you have? If you have the pro based cameras you can disable P2P and DLNA (I believe DLNA is disabled by default)

I also have a ton of domains that I wanted to be able to receive email on. In my case, I was the only recipient so I just needed a provider that let me setup aliases.

Fastmail is pretty affordable. All plans except the business basic plan allow you to setup 100 custom domains which you can the forward to your mailbox.

Their mail app is pretty solid. I particularly like that it lets you receive notifications for email that's been moved to another folder. Which I've had troubles with on other emails apps. I also really like that I can use a custom domain for random masked emails.