Because it is worth it. It is a considerable source of advantage if you send millions of emails at a small fixed cost.
There is nothing like emails. Your users will love you if you send useful customized emails. This is what I love about Basecamp. This is what our users love about Screener.in.
Sending customized automated emails require scalability. And it is not very scalable if we are paying money for sending each email.
| Emails per day | Amazon SES | Mailgun | Own server |
|---|---|---|---|
| 1,000 | $3 | $24 | $5 |
| 10,000 | $30 | $215 | $5 |
| 100,000 | $300 | --- | $5 |