SMTP (Simple Mail Transfer Protocol)
The standard protocol used for sending emails between servers across the internet.
What is SMTP (Simple Mail Transfer Protocol)?
SMTP (Simple Mail Transfer Protocol) is the standard protocol that handles sending emails across the internet. When you send an email, it travels through SMTP servers before reaching the recipient.
How SMTP works: 1. You compose email in your client (Outlook, Gmail) 2. Your client sends to your outgoing SMTP server 3. Your SMTP server looks up recipient's MX records 4. Your server connects to recipient's server via SMTP 5. Recipient's server accepts (or rejects) the email
Key SMTP concepts:
- Port 587: Standard submission port (with TLS)
- Port 25: Server-to-server relay (often blocked)
- TLS encryption: Secures the connection
- Authentication: Proves you're authorized to send
For cold email, you rarely interact with SMTP directly - your email provider (Microsoft 365, Google) handles it. But understanding SMTP helps diagnose delivery problems.
Why It Matters
- 1Foundation of how all email works
- 2Understanding helps diagnose delivery issues
- 3SMTP errors indicate specific problems
- 4Rate limits often enforced at SMTP level
Related Terms
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