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networking/mail/mail-smtp.md

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+# SMTP (Simple Mail Transfer Protocol)
+
+**SMTP (Simple Mail Transfer Protocol)** is a networking protocol for [mail](mail.md) transfer. It's used to send emails from a mail client to a mail server and between mail servers.
+
+Server-to-Server communication is typically done over port `25`. Client-to-Server communication is typically done over port `587`. Alternatively, port `465` can be used for client-to-server communication with [TLS](../tls.md).
+
+## Configuration
+
+### SMTP Server
+
+The SMTP server is a mail server that receives emails from a mail client and forwards them to their intended recipients. It's also responsible for receiving emails from other mail servers and delivering them to their intended recipients.
+
+### SMTP Client
+
+The SMTP client is a mail client that sends emails to a mail server for delivery. It's also responsible for receiving emails from other mail servers and delivering them to their intended recipients.
+
+## Troubleshooting
+
+[SMTP Troubleshooting Cheat Sheet](smtp-troubleshooting.md)
+
+## References
+
+- [SMTP (Simple Mail Transfer Protocol)](https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol)