as per Twitch TOS:

9.iii. make unsolicited offers, advertisements, proposals, or send junk mail or spam to users of the Twitch Services, including, without limitation, unsolicited advertising, promotional materials, or other solicitation material, bulk mailing of commercial advertising, chain mail, informational announcements, charity requests, petitions for signatures, or any of the preceding things related to promotional giveaways (such as raffles and contests), and other similar activities;