

On many trackers, you get “paid” for time seeded. Usually in the forms of bonus points or the like. You can then exchange these for improving your ratio (or a freeleech token, or an invite,…).
It’s a system that also rewards keeping media available even if you are not uploading to anyone.
Also, keep in mind that often, a large part of the available content is freeleech (meaning leeching it doesn’t affect your ratio), but seeding those torrents usually still does improve your ratio.
FWIW, I have no issues sending mails/having them be received from my self-hosted to Google mail