Deliverability beats the per-email rate
Email sends are cheap; landing in the inbox is the hard part. Weigh reputation and authentication over a fraction of a cent. Compare the SMS channel on the SMS cost calculator.
Email API pricing beyond the sticker
Transactional email prices cluster around $0.50–$1.00 per thousand sends at volume, but the effective price depends on what's bundled: dedicated IPs ($20–$80/month each) become mandatory at scale for deliverability, inbound parsing often bills separately, and validation APIs cost as much per check as a send. The deliverability tax is the hidden line — a provider $0.20/1k cheaper that lands 2% more of your mail in spam costs far more in lost signups than it saves. Free tiers (100–3,000/day) genuinely cover most side projects; the paid decision starts around 100k sends monthly.