Should big companies publicly list their legit emails and links?

I’ve been going through a hassle with a big mobile company about if I should click into a link in an email that I think is from them. The email and the link inside is not obviously from the company, as the domains do not match up to the providers domain, or alternate domains. It seems through discussion on the company forum that it’s not clear that this email is legit. This has been a confusing situation.

Should large companies have a security standards page, wherein they list all legit emails and domains that belong or are associated with them? For someone like me who checks the sender email and the domain of the links within it, I want to know who they are. If the company listed them on their website I would feel instantly safe. But instead I’ve wasted hours trying to resolve this situation without an answer yet.

My question – does such a scheme exist to list legit emails/domains on company websites? If not, why? If so, where?