Manually set avatar for a domain?

My company domain has a favicon that’s low resolution, so all emails from addresses at that domain (that aren’t people in my contacts) have an avatar that shows up with low resolution and looks bad.

Can I manually set an avatar for a given domain, e.g., from a local file on my computer?

Does eM Client only look at favicon.ico, or are there other URLs it checks on a site for an avatar? (Perhaps I could ask my company to upload another file that has higher resolution, although I doubt I could get them to modify favicon.ico)