I wouldn’t bother with a home assistant if your sister is non technical.
I use both xeoma with raw rtsp stream and tapo app. any app that uses rtsp should work

Just get her SD card and use a tapo app.

Does she have regular 12 volt doorbell?
Get her wired doorbell camera this way no batteri s needed. And a large sd card.
I use tapo and it’s fine.

I’m not sure I’m following your point. This tool is not sending emails from non warmed up ips. you supposed to be using a provider.
I’ve used many esp over the years and they all just use ses or mailgun or postmark under the hood. There is no difference from this tool

I’m not sure why you think this way? This is for managing newsletters - he’s not sending directly from this tool.
smtp and ses and sendgrid are used for actual mailing.

That don’t seem to apply to plex pass. Those limitations. I have a plex pass

Wait - what restrictions on Plex?