Several applications, like security camera or home alarm systems, can trigger emails. But building a mail server using your Pi is a project of its own! All you need is a Raspberry Pi and an email. Before you embark on this, you must understand the challenge it poses. An independent e-mail server will not be as adept as a commercial e-mail provider. This is because most connections do not have static IP address. Commercial servers use static IP addresses to ensure that it is permanently accessible. Having dynamic IP address may prompt the recipient’s e-mail server often views messages as spam mails if they are sent via an internet connection with a dynamic IP address.

There are several tutorials available to build your mail server using Raspberry Pi, here is an easy one. The prerequisites are simple and this is an easy-to-build first project!

A print server connects client devices with printers within a network. It accepts print requests from the devices and queues and sends them to the appropriate printer. This is especially in commercial environments, wherein several users may be using a single printer. For instance, within an office where the requests may arrive more rapidly than the printer alone can handle. Setting up a printer server using your Raspberry Pi is a easy and economic way to upgrade your USB printer to wireless. This project uses CUPS – Common Unix Printing System, which basically is able to receive, recognise and send requests to the printer. CUPS supports most printers, but before getting started on this project you can check here to see if your printer is supported as well.

Opensource has a great article on how to set up an easy print server using your Raspberry Pi.

Media servers, true to its name makes media available to stream on any device within a network. These servers are huge for Video on Demand services, and smaller and simpler within a closed private network like your house. Your Raspberry Pi can also be used as a server to stream video and music to other devices around your home. There is a plenty of different software available to download. You can stream pictures, videos, music and even movies on your devices at the touch of a button. The great thing about this is, the set up fast and easy to understand. You can have a Raspberry Pi media server ready to go in just a few minutes.

This is a helpful tutorial that offers several choices for you to pick from and build your media server, depending on the type of media you want to stream.

Network-attached storage (NAS) is a remote data storage and access unit. It allows devices across a network to store information and access it, and can even have various levels of permission and accessibility. However, these are often commercial and expensive for private usage. But here’s the good news. If you just seem to have an external hard disk or two lying around with your Raspberry Pi – you can convert it into an NAS unit. You can even use a USB drive or an SD card depending on the space you want. The process however doesn’t change regardless of the size of stage you are connecting. In case you do have two devices, you can even use one of them as a backup in case one fails.

The tutorials for this are often easy to follow and involve only a few steps. Here is one with great explanations and easy to understand steps.

Web server is basically a storage center for web content. These servers can be used to host static or dynamic websites. In function it is similar to that of the servers we previously saw, it receives request and sends data pertaining to that request. Since these are often confused with websites, we must understand what a ‘website’ means. A website is collection of web pages, whereas a web server is a tool that responds to a smart device requesting for resources. You use your Raspberry Pi web server to host a website or to share some data to other devices connected to the same network.

There are quite a few web server software available. The most popular, Apache is ideal for most web server applications. Here is a tutorial that is a part of the official documentation, which explains hot to install and start using both Apache and NGINX.