Outgoing and incoming mail server

In the context of email, an outgoing mail server and an incoming mail server are two critical components that enable email communication.

Outgoing Mail Server (SMTP):

The outgoing mail server, also known as the Simple Mail Transfer Protocol (SMTP) server, is responsible for sending emails from your email account to the recipient's email account. When you compose an email and click the "Send" button, your email client (e.g., Gmail, Outlook) connects to the outgoing mail server to transmit the email.

The outgoing mail server's primary function is to:

  1. Receive emails from your email client
  2. Authenticate your email account credentials (username and password)
  3. Route the email to the recipient's email server
  4. Deliver the email to the recipient's inbox

Incoming Mail Server (POP3/IMAP):

The incoming mail server, also known as the Post Office Protocol version 3 (POP3) or Internet Message Access Protocol (IMAP) server, is responsible for retrieving emails from the recipient's email server and delivering them to your email client.

The incoming mail server's primary function is to:

  1. Receive emails from the recipient's email server
  2. Authenticate your email account credentials (username and password)
  3. Download emails from the server to your email client
  4. Store emails locally on your device

Key differences:

  1. Direction: Outgoing mail server sends emails, while incoming mail server receives emails.
  2. Authentication: Both servers require authentication using your email account credentials.
  3. Functionality: Outgoing mail server focuses on sending emails, while incoming mail server focuses on retrieving emails.

Common scenarios:

  1. POP3: Your email client connects to the incoming mail server (POP3) to download emails, and then deletes them from the server. This is suitable for users who only need to access their emails on a single device.
  2. IMAP: Your email client connects to the incoming mail server (IMAP) to download emails, and then keeps a copy on the server. This is suitable for users who need to access their emails from multiple devices or want to keep a copy of their emails on the server.

In summary, the outgoing mail server (SMTP) is responsible for sending emails, while the incoming mail server (POP3/IMAP) is responsible for retrieving emails. Both servers play crucial roles in enabling email communication.