This is exactly what was mentioned here as well: Ability to set Static/Constant Custom Values per Email Integration "Connected account" (when there are multiple connected accounts synced by same person)
This sounds like quite needed functionality, I hope it gets attention soon, it makes a lot of sense as it’s important data.
I think they shouldn’t, and should be handled the same way “Synced by” is handled when different Fibery users sync their personal emails, its a to-many relation. So if two users have the same email, it shows that both of them synced it.
This is due to the way integrations work. There’s 1 “main” account synced, then the email integration (and maybe a few others?) have the ability to add multiple accounts. But this is not common across the board.
I had no idea Notion sunset the email app.