Reasons for selection

WebArena Indigo

In conclusion, Overwhelming Const Performance!

I originally planned to build a mail server on Sakura VPS, but in order to run Mailu with antivirus software and other software A minimum of 3 GB of memory was required.

At the time of writing (March 2022), the cheapest Ishikari region will cost 3,530 yen/month if the memory is 3GB or more.

That’s a bit expensive, isn’t it? Then I remembered that one of my customers used to use WebARENA Indigo VPS, and I checked it out. It’s a pay-as-you-go system.

• 4GB memory
• SSD 80GB

and even if it is running all the time, the maximum cost is 1,272 yen/month.

It is about 1/3 the price and has less SSD capacity, but considering that it is a mail server, this was a much better choice.

Translated with www.DeepL.com/Translator (free version)

Mailu

In the words of the official website

Mailu is a simple yet full-featured mail server as a set of Docker images.
It is free software (both as in free beer and as in free speech), open to suggestions and external contributions.
The project aims at providing people with an easily setup, easily maintained and full-featured mail server while not shipping proprietary software nor unrelated features often found in popular groupware.

So it looks very easy to use.

Specifically.

• Standard mail servers such as IMAP, IMAP+, SMTP
• Aliases, domain aliases, and custom routing
• Web-accessible administrator screen
• Auto-reply and auto-forward
• TLS, auto-signature with Let’s Encrypt, DKIM, antivirus
• Anti-spam measures such as greylisting, DMARC, SPF

are supported.

Moreover, you can create a configuration file with GUI. It’s great!

I was originally going to use Docker-Mailserver, but I gave up because I couldn't get emails, even though I followed the instructions.

Cloudflare

This is what I used to build my original personal website (this site).

You can buy domains at wholesale prices, so I went to Cloudflare Register to purchase a domain and set up DNS as well.

Build a server

setup environment

I selected Ubuntu 18.04 as the OS.

WebArena Indigo provides web access to the console. According to here, the first time you boot

• Username: ubuntu
• Password: none (enter without typing anything)

However, it seems to fail in any way, so I decided to connect from my local terminal with ssh.

# install git, etc
sudo apt-get update
sudo apt-get install -y git vim curl wget unzip zip gnupg lsb-release ca-certificates

# install docker
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io

# install docker-compose
sudo curl -L "https://github.com/docker/compose/releases/download/1.26.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose

Finish the installation of docker-compose as follows.

Mailu setup

You can use Mailu configuration to configure the settings from the GUI.

When you have finished entering all the information, enter Setup Mailu and follow the steps displayed to publish.

When you are done setting up, type

# start up the server first
$ sudo docker-compose -p mailu up -d

# You must first create one user to connect to the server.
# You can create an account called [email protected] with a password of PassWord with the following command
$ sudo docker-compose -p mailu exec admin flask mailu admin admin admin1 test.com PassWord

# The following command will also create an account named [email protected] with no administrative privileges
$ sudo docker-compose exec admin flask mailu user nagata test.com PassWord2

Configure DNS

Once the server is created, we move on to DNS configuration.

Minimum routing, etc.

A Record

Use the A record to direct the part of the email address after the @ to the server you created above.

mail.test.com.	1	IN	A	144.144.144.144

If you are using Cloudflare, you can use

You can make it test.com instead of mail.test.com, but I feel it is better to make it mail..

MX Record

Configure name resolution with email.

mail.test.com.	1	IN	MX	0 mail.test.com.

If you are on Cloudflare

If you want to receive mail sent to test.com as well, use the

mail.test.com.	1	IN	MX	10 mail.test.com.

or

And you can receive it by adding test.com to Mail Domains > Alternatives (Manage tab) from the Mailu admin screen.

Certificate

With the above settings, DKIM and SPF are not configured. This means that they may be sorted into spam or not be received (gmail did not receive them).

So set the information appropriately.

From the admin screen, go to Mail Domains > Details (Actions tab) and Regenerate keys to generate the appropriate entries.

You can set everything except the DKIM public key to DNS for proofing.

Cloudflare is a GUI entry, so it’s hard to do, but you can add it all at once by copying it all into a txt file in notepad or something, then importing it from Advanced.

Test

You can email to a Gmail account and make sure it is not being sorted into spam.

To learn more about it, I recommend the following site.

https://www.appmaildev.com/en/dkim

Email to the email address shown after pressing Next Step.

It will tell you if each test passed, and you can easily correct it if it’s wrong.

Conclusion

By following these steps, you can easily build a mail server.

I highly recommend this and encourage you to give it a try.