Mail server deployment for an organization depends on many things like, the organization’s size, business requirements, the volume of email, etc. it can be a single standalone machine. or it could be a complex distributed setup. Here, we will discuss the design and deployment requirements for configuring a complete mail server with a single machine. this setup is ideal for small organizations, where users are sending and receiving mail by using the same server.
Mail server can be deployed as internet-facing or behind a firewall. both scenarios have different preparations, advantages and disadvantages. we will try to clear both scenarios.
To install and configure a Linux mail server, we need to follow the basic steps below.
Linux Mail Server Configurations basic steps:
- Install the Preferred OS
- Assign static IP
- Assign Hostname as FQDN.
- Install MTA
- Install POP/IMAP Service
- Install Webmail.
- Install Email filter App, and Finally
- Configure DNS A and MX record for the domain.
Linux Mail Server basic operations:
- Send/Receive Emails
- Provide Email Storage
- Provide Webmail Service
- Spam Filtering During Send/Receive
Mail Server Setup with a public IP (Scenario-1)
In this diagram, we deployed our server as internet-facing, with a public IP (18.104.22.168). the server hostname is “mailer.mailserverguru.com”. this mail server is performing the basic operations mentioned above.
How the email will flow and server delivers mail
1. As this server needs to receive mail from the internet, at the DNS we have pointed this server as the only MX server for our domain.
2. The Server receives the mail and stored in the specified mail storage location or Inbox.
3. Users are pulling mail to their Outlook by connecting to the POP/IMAP service. POP/IMAP service will retrieve mail from the inbox and delivers to user’s desktop.
4. Users can access the webmail to send/receive emails from the web browser.
5. Users will send mail through this server, it will receive mail from the local user and deliver it to the destination server.
6. during send/receive all emails are scanned & filtered by the email scanner installed at the server, this is an optional service because sometimes organizations liked to take email filtering services from third-party providers.
For Quick standalone Linux mail server configuration, watch this video
For Details on Linux mail server configuration watch this one.
Mail Server Setup with Lan IP (Scenario-2)
In this scenario, Our server configuration has slight change. Now it has two Lan cards, one for the local network and the other for the public internet. The key advantage of this design is that local users can send/receive mail to the server with a private IP address, even if the internet connection is down. They can also mail each other within the office without using the public internet because they will have wire-speed access to the server. To set up the mail server with this design, we must set up all of the services to listen on all of the server’s available IPs.
To access the server with the same hostname from both public and private networks, we can have a local DNS server for name resolution with private IP, as we already mapped hostname with public IP at the Public DNS.
So, to configure a standalone mail server we need to install & configure the following components,
– SMTP server or MTA
– POP/Imap Server
– Webmail Server
– and Optionally Spam Filter.