What's a mail server
A mail server is a computer system that handles email messages and routes them to their intended recipients. It's a crucial component of the email infrastructure, allowing users to send and receive emails.
A mail server typically performs the following functions:
- Receiving emails: It accepts incoming emails from other mail servers or users and stores them in a database.
- Storing emails: It stores emails in a database or file system, often organized by user or domain.
- Routing emails: It routes emails to their intended recipients, either by delivering them directly to the recipient's email client or by forwarding them to another mail server.
- Delivering emails: It delivers emails to the recipient's email client, such as Microsoft Outlook, Mozilla Thunderbird, or a web-based email client like Gmail.
- Managing email accounts: It manages email accounts, including creating, deleting, and modifying user accounts, as well as setting up email forwarding and autoresponders.
- Spam and virus filtering: It filters out spam and viruses from incoming emails to prevent them from reaching users' inboxes.
- Backup and recovery: It provides backup and recovery mechanisms to ensure that emails are not lost in case of a system failure or data corruption.
Mail servers can be categorized into two main types:
- Mail Transfer Agent (MTA): An MTA is responsible for transferring emails between mail servers. Examples of MTAs include Postfix, Sendmail, and Exim.
- Mail Delivery Agent (MDA): An MDA is responsible for delivering emails to users' email clients. Examples of MDAs include Procmail and Fetchmail.
Some common mail server protocols include:
- SMTP (Simple Mail Transfer Protocol): Used for sending and receiving emails between mail servers.
- POP3 (Post Office Protocol version 3): Used for retrieving emails from a mail server to a user's email client.
- IMAP (Internet Message Access Protocol): Used for retrieving and managing emails on a mail server.
Mail servers can be hosted on-premises or in the cloud, and they can be managed manually or using automation tools.