What is mail server
A mail server is a computer system that handles email messages and provides email services to users. It is a critical component of the email infrastructure, responsible for receiving, storing, and forwarding email messages between users.
A mail server typically performs the following functions:
- Receiving emails: It receives email messages from other mail servers, the internet, or local users.
- Storing emails: It stores email messages in a database or file system, often organized by user or folder.
- Forwarding emails: It forwards email messages to the intended recipients, either locally or remotely.
- Delivering emails: It delivers email messages to the user's email client, such as Microsoft Outlook or Mozilla Thunderbird.
- Managing email accounts: It manages email accounts, including creating, deleting, and modifying user accounts, passwords, and email settings.
- Filtering and routing: It filters and routes email messages based on various criteria, such as sender, recipient, subject, and content.
- Spam and virus protection: It scans email messages for spam and viruses, and blocks or quarantines suspicious messages.
Mail servers can be categorized into two main types:
- Mail Transfer Agent (MTA): An MTA is responsible for transferring email messages between mail servers. Examples of MTAs include Sendmail, Postfix, and Exim.
- Mail Delivery Agent (MDA): An MDA is responsible for delivering email messages to the user's email client. Examples of MDAs include Procmail and Fetchmail.
Some common mail server protocols include:
- SMTP (Simple Mail Transfer Protocol): Used for sending and receiving email messages between mail servers.
- POP3 (Post Office Protocol version 3): Used for retrieving email messages from a mail server to a user's email client.
- IMAP (Internet Message Access Protocol): Used for retrieving and managing email messages on a mail server.
Mail servers can be hosted on-premises or in the cloud, and can be managed by IT administrators or third-party service providers.