Internet email has several layers: addressing and routing, outbound sending, and inbound mailbox access. The Application Platform focuses on outbound delivery over SMTP.
SMTP (Simple Mail Transfer Protocol)
- Role: Server-to-server (and client-to-server) message transport—typically outbound from your system to the recipient’s mail server.
- On the platform: SMTP credentials describe this connection: your service authenticates to a relay (for example Mailtrap) and hands off the message.
- Common ports:
- 587 with STARTTLS (common for authenticated “submission”)
- 465 with TLS (legacy but still used)
- 25 is often unauthenticated server-to-server relay (less relevant for app credentials)
IMAP (Internet Message Access Protocol)
- Role: Synchronized access to a mailbox on the server (folders, flags, multiple clients).
- On the platform: Not part of the SMTP credential form; IMAP is configured in mail clients or another service, not in this SMTP entry.
POP3 (Post Office Protocol version 3)
- Role: Download messages, classically “fetch and optionally delete from server”.
- On the platform: Also not the same configuration as SMTP; POP3 concerns inbound mailboxes, not transactional relay sending.
Webmail and HTTP APIs
- Webmail in the browser usually speaks HTTPS to a provider; SMTP/IMAP may run behind the scenes but is hidden from app developers.
- Many providers also offer REST APIs alongside SMTP. The platform stores SMTP here; an HTTP API would be wired separately in application code.
Quick decision table
| Goal | Protocol / place |
|---|---|
| App sends notification email | SMTP (platform credential) |
| App reads a user’s inbox | IMAP or provider REST (outside this SMTP form) |
| End user reads mail in browser | Webmail / provider UI |