¿Qué es SMTP?
SMTP (Simple Mail Transfer Protocol) is the standard protocol used to send emails across the internet. It handles the transmission of email from the sender's mail server to the recipient's mail server. SMTP works in conjunction with IMAP or POP3, which handle receiving and storing emails.
Cómo Funciona
When you send an email, your mail client connects to an SMTP server on port 25 (or 587/465 for secure connections). The SMTP server looks up the recipient's MX records via DNS, establishes a connection to the destination mail server, and transfers the message using a series of commands (HELO, MAIL FROM, RCPT TO, DATA).
Por Qué Importa
SMTP is the backbone of email communication. Understanding how it works helps diagnose delivery failures, configure mail servers correctly, and ensure secure email transmission with TLS encryption.
Problemas Comunes
- SMTP connection timeouts
- Port 25 blocked by ISP or firewall
- Missing STARTTLS causing unencrypted transmission
- Authentication failures on SMTP relay
- HELO/EHLO hostname mismatch