Main difference is rate limits and purging.
The free relay is rate-limited and may purge data over time, with best-effort uptime.
On the premium relay, payment itself is the spam prevention. It has guaranteed uptime, no rate limits, and no purging.
The free relay is rate-limited and may purge data over time, with best-effort uptime.
On the premium relay, payment itself is the spam prevention. It has guaranteed uptime, no rate limits, and no purging.