What does a mail server do

A mail server is a computer system that handles email messages and routes them to their intended recipients. Its primary function is to store, forward, and deliver email messages between email clients, such as email providers, webmail services, and email clients on devices.

Here are some of the key tasks that a mail server performs:

  1. Receiving email: The mail server receives email messages from email clients, such as email providers, webmail services, and email clients on devices.
  2. Storing email: The mail server stores the received email messages in a database or file system, often organized by user or domain.
  3. Filtering email: The mail server applies filters to incoming email messages to determine their relevance, authenticity, and priority. This helps to prevent spam, viruses, and other malicious content from reaching users.
  4. Routing email: The mail server routes email messages to their intended recipients, either within the same domain or to external domains.
  5. Delivering email: The mail server delivers email messages to the recipient's email client, either directly or through a relay server.
  6. Managing email accounts: The mail server manages email accounts, including creating, deleting, and modifying user accounts, as well as setting password policies and access controls.
  7. Providing email services: The mail server provides various email services, such as:
    • POP3 (Post Office Protocol version 3) and IMAP (Internet Message Access Protocol) for retrieving email messages.
    • SMTP (Simple Mail Transfer Protocol) for sending email messages.
    • Webmail access for users to access their email accounts through a web interface.
  8. Monitoring and maintenance: The mail server continuously monitors its performance, logs, and configuration to ensure optimal operation and troubleshoot any issues that may arise.

Mail servers can be categorized into different types, including:

  1. Mail Transfer Agents (MTAs): These servers primarily focus on transferring email messages between domains.
  2. Mail Delivery Agents (MDAs): These servers primarily focus on delivering email messages to user mailboxes.
  3. Mail User Agents (MUAs): These servers primarily focus on providing email services to users, such as webmail access and email client integration.

Some popular mail server software includes:

  1. Postfix
  2. Sendmail
  3. Exim
  4. Qmail
  5. Microsoft Exchange
  6. Zimbra
  7. OpenSMTPD

In summary, a mail server plays a crucial role in the email ecosystem, ensuring that email messages are delivered efficiently and securely to their intended recipients.