[gerardnico]

It's a front-end application around a SMTP mail server. https://datacadamia.com/marketing/email/server You take your favorite language and you build your own. That's hard ... ip control (they may be blacklisted), high availability, bounce and other features requires a lot of work. The easy way is to create your application around a transactional email service. You pay for the email but not for the application :)

[rails]

Do you know of any articles or information in general, how these hard things (ip control, bounce, ...) are done?

[gerardnico]

Bounce is an email send by the server when it can deliver an email. You just need to parse it.

Ip control is generally done via the dmarc report that you also get as email from email provider. https://datacadamia.com/marketing/email/dmarc