Anything that allows sending emails with custom content will attract spammers. We aggressively limited the free accounts, and that still attracted spammers who

Anything that allows sending emails with custom content will attract spammers. We aggressively limited the free accounts, and that still attracted spammers who would just create loads of news accounts to send out emails; we eventually put a stop to it by limiting it to 25 recipients in total, after which they finally gave up (before, it was 25 emails with a max of 10 recipients each, which meant 250 spam emails).