Ask HN: Access all my emails with one login:what online web app/client is there?

Hi HN,

I have over 10 email addresses. I'm in fact not making any more email addresses because of this simple reason: I have them all linked on my phone and on my laptop (through the Mac client), but once I switch over to a new device, I need to:

1. Log in to all of them 2. Set all the signatures again manually 3. Make sure all the signatures are synced everywhere 4. Set all the display names the same

Make a change and I need to go to all my devices.

What app/service is there that would allow me to go on it, maybe through the browser, and through one login (logging in to that service), I'd see all my email addresses?

I've been searching for one but maybe I don't get the keywords right