How to Quickly Set Up a Mail Server on Debian 10 Buster With Modoboa

Setting up a mail server on Linux from scratch is a pain in the neck. This tutorial is going to show you how to quickly set up your own email server on Debian 10 Buster with Modoboa, saving you lots of time and headaches. Modoboa is a free and open-source mail hosting and management platform designed to work with Postfix SMTP server and Dovecot IMAP/POP3 server.

Modoboa is written in Python, released under the terms of ISC license. At the time of writing, The latest version is v1.16.0, released on October 5, 2020. Main features of Modoboa are as follows:

  • Modoboa by default uses Nginx web server to serve the webmail client and web-based admin panel.
  • Compatible with Postfix and Dovecot.
  • Supports MySQL/MariaDB, and PostgreSQL database.
  • Easily create unlimited mailboxes and unlimited mail domains in a web-based admin panel.
  • Easily create email alias in the web-based admin panel.
  • The webmail client provides an easy-to-use message filter to help you organize messages to different folders.
  • It can help you protect your domain reputation by monitoring email blacklists and generating DMARC reports, so your emails have a better chance to land in the inbox instead of the spam folder.
  • Includes amavis frontend to block spam and detect viruses in email.
  • Calendar and address book.
  • Integration with Let’s Encrypt to get a valid SSL/TLS certificate.
  • A policy daemon for Postfix that allows you to define daily sending limits for domains and individual accounts.
  • Includes AutoMX to allow end-users to easily configure mail account in a desktop or mobile mail client.

Step 1: Choose the Right Hosting Provider and Buy a Domain Name

To set up a complete email server with Modoboa, you need a server with at least 2GB RAM, because after the installation, your server will use more than 1GB of RAM. This tutorial is done on a $11.99/month Contabo VPS (virtual private server). I recommend Contabo because it does not block port 25, so you can send unlimited emails (transactional email and newsletters) without spending money on SMTP relay. Contabo doesn’t have any SMTP limits. You can send a million emails per day.

Other VPS providers like DigitalOcean blocks port 25. DigitalOcean would not unblock port 25, so you will need to set up SMTP relay to bypass blocking, which can cost you additional money. If you use Vultr VPS, then port 25 is blocked by default. They can unblock it if you open a support ticket, but they may block it again at any time if they decide your email sending activity is not allowed. Vultr actually may re-block it if you use their servers to send newsletters.

Go to Contabo website to create an account. Choose the 2GB unmanaged Linux VPS plan.

VPS hosting for email

Once you created an account, Contabo will send you an email with the server SSH login details. To log into your server, you use an SSH client. If you are using Linux or MacOS on your computer, then simply open up a terminal window and run the following command to log into your server. Replace with your server’s IP address.

ssh [email protected]

You will be asked to enter the password. I recommend following the tutorial linked below to properly set up your Linux VPS server on Contabo.

It is highly recommended that you follow the instructions below on a clean install of Debian 10 OS.

You also need a domain name. I registered my domain name from NameCheap because the price is low and they give whois privacy protection free for life.

Step 2: Creating MX Record and A Record in DNS

The MX record specifies which host or hosts handle emails for a particular domain name. For example, the host that handles emails for is If someone with a Gmail account sends an email to [email protected], then Gmail server will query the MX record of When it finds out that is responsible for accepting email, it then queries the A record of to get the IP address, thus the email can be delivered.

You can log in to your domain registrar’s website (such as NameCheap) to create DNS records.

In your DNS manager, create an MX record for your domain name. Enter @ in the Name field to represent the main domain name, then enter in the Value field.

modoboa web interface

Note: The hostname for MX record can not be an alias to another name. Also, It’s highly recommended that you use hostnames, rather than bare IP addresses for MX record.

Your DNS manager may require you to enter a preference value (aka priority value). It can be any number between 0 and 65,356. A small number has higher priority than a big number. You can enter 0 for your email server, or accept the default value.

After creating MX record, you also need to create an A record for , so that it can be resolved to an IP address. If your server uses IPv6 address, be sure to add AAAA record.

If you use Cloudflare DNS service, you should not enable the proxy (CDN) feature when creating A record for your mail server. Cloudflare does not support SMTP proxy. You won’t be able to receive emails if you enable the proxy feature.

Step 3: Set up Mail Server on Debian 10 Buster with Modoboa Installer

Log into your server via SSH, then run the following command to update existing software packages.

sudo apt update

sudo apt upgrade

I strongly recommend creating a sudo user for managing your server rather than using the default root user to improve server security. Run the following command to create a user. Replace username with your preferred username.

adduser username

adduser scalahosting

Then add the user to the sudo group.

adduser username sudo

Switch to the new user.

su - username

You Debian 10 system might ship with Exim SMTP server. Since Modoboa will use Postfix SMTP server, we need to remove Exim.

sudo apt remove exim4 exim4-base exim4-daemon-light

Download Modoboa installer from Github.

sudo apt install git

git clone

Modoboa is written in Python. Run the following command to install the necessary Python software.

sudo apt-get install python3-virtualenv python3-pip

Then navigate to the modoboa-installer directory and create a configuration file. Replace with your own domain name.

cd modoboa-installer

sudo ./ --stop-after-configfile-check


Edit the configuration file installer.cfg with a command-line text editor like nano.

sudo nano installer.cfg

To obtain a valid TLS certificate from Let’s Encrypt for your mail server, in [certificate] section, change the value of type from self-signed to letsencrypt.

type = letsencrypt

And change the email address from [email protected] to your real email address, which will be used for account recovery and important notifications. You will not be able to obtain and install Let’s Encrypt certificate if you use the default email address.

modoboa installer

By default, Modoboa installer will install PostgreSQL database server, as indicated by the following lines in the config file.

engine = postgres
host =
install = true

If you would like to use MariaDB database server, then change the engine from postgres to mysql. (Modoboa will install MariaDB instead of MySQL.)

modoboa mariadb database

To save the file in Nano text editor, press Ctrl+O, then press Enter to confirm. Press Ctrl+X to exit.

Next, you should use a fully-qualified domain name (FQDN) as the hostname for your mail server, such as Run the following command to set the hostname.

sudo hostnamectl set-hostname

Now we need to verify if the DNS records are propagated to the Internet. Depending on the domain registrar you use, your DNS record might be propagated instantly, or it might take up to 24 hours to propagate. You can go to, enter your mail server’s hostname ( to check DNS propagation.

If your DNS record are propagated, run the following command to start the installation.

sudo ./ --interactive


The installation process can take a while. It took 10 minutes on my Contabo server. If you experience an error during the installation, you can use the --debug option to see more detailed output.

sudo ./ --interactive --debug

After Modoboa finishes installation, you can log into the admin panel with username admin and password password. (If your browser can’t connect to the admin panel, it could be that Nginx is not running. Start it with sudo systemctl restart nginx.)


Once you are logged in, you should go to Admin -> Settings -> Profile to change the password.

modoboa install

Step 4: Adding Mailboxes in Modoboa Admin Panel

Please note that the default admin account isn’t an email account. It can only be used to administer the mail server. To send emails, you need to add mailboxes with the admin account.

Go to Domains tab and click Add button to add a new domain.

modoboa review

Then enter your main domain name in the Name field. It is highly recommended that you enable DKIM signing, which can help with your domain reputation. In Key selector filed, you can enter a random word like modoboa. Choose 2048 for the key length.

adding domain name in modoboa

In the next screen, you can choose to create an admin account for this particular domain name. The SMTP protocol requires that a mail server should have a [email protected] address.

modoboa postmaster account

Click the Submit button and your domain name will be added in Modoboa.

To add email addresses, go to Domains tab and click your domain name.

add mailboxes in modoboa

Then click mailboxes.

adding email addresses in modoboa

Click Add button and choose Account.

modoboa alias

Then choose Simple user as the role. Enter an email address in Username field and enter a password.

qucikly set up an email server modoboa

In the next screen, you can optionally create an alias for this email address.

create alias in modoboa

After clicking the submit button, the email address is created.

Step 5: Sending Test Emails

To login to the webmail, you need to log out the admin account first and then enter the user credentials.

modoboa login

Once you are logged into Modoboa webmail, you can send a test email from your private email server to your other email address and vice versa.

modoboa webmail

Inbound emails will be delayed for a few minutes because by default Modoboa enables greylisting, which tells other sending SMTP server to try again in a few minutes. This is useful to block spam. The following message in /var/log/mail.log indicates greylisting is enabled.

postfix/postscreen[20995]: NOQUEUE: reject: RCPT from []:36980: 450 4.3.2 Service currently unavailable;

However, greylisting can be rather annoying. You can disable it by editing the Postfix main configuration file.

sudo nano /etc/postfix/

Find the following lines at the end of the file and comment them out. (Add a # character at the beginning of each line.)

postscreen_pipelining_enable = yes
postscreen_pipelining_action = enforce

postscreen_non_smtp_command_enable = yes
postscreen_non_smtp_command_action = enforce

postscreen_bare_newline_enable = yes
postscreen_bare_newline_action = enforce

Save and close the file. Then restart Postfix for the changes to take effect.

sudo systemctl restart postfix

Now you should be able to receive emails without waiting several minutes.

Adding Swap Space

ClamAV is used to scan viruses in email messages. ClamAV can use a fair amount of RAM. If there’s not enough RAM on your server, ClamAV won’t work properly, which will prevent your mail server from sending emails. You can add a swap file to your server to increase the total RAM on your server. (Note that using swap space on the server will degrade server performance. If you want better performance, you should upgrade the physical RAM instead of using swap space.)

To add swap space on the server, first, use the fallocate command to create a file. For example, create a file named swapfile with 1G capacity in root file system:

sudo fallocate -l 1G /swapfile

Then make sure only root can read and write to it.

sudo chmod 600 /swapfile

Format it to swap:

sudo mkswap /swapfile


Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=0aab5886-4dfb-40d4-920d-fb1115c67433

Enable the swap file

sudo swapon /swapfile

To mount the swap space at system boot time, edit the /etc/fstab file.

sudo nano /etc/fstab

Add the following line at the bottom of this file.

/swapfile    swap    swap     defaults    0   0

Save and close the file. Then reload systemd and restart ClamAV.

sudo systemctl daemon-reload

sudo systemctl restart clamav-daemon

Step 6: Checking If Port 25 (outbound) is blocked

Your ISP or hosting provider won’t block incoming connection to port 25 of your server, which means you can receive emails from other mail servers. However, many ISP/hosting providers block outgoing connection to port 25 of other mail servers, which means you can’t send emails.

If your email didn’t arrive at your other email address such as Gmail, then run the following command on your mail server to check if port 25 (outbound) is blocked.

telnet 25

If it’s not blocked, you would see messages like below, which indicates a connection is successfully established. (Hint: Type in quit and press Enter to close the connection.)

Connected to
Escape character is '^]'.
220 ESMTP y22si1641751pll.208 - gsmtp

If port 25 (outbound) is blocked, you would see something like:

Trying 2607:f8b0:400e:c06::1a...
Trying telnet: Unable to connect to remote host: Connection timed out

In this case, your Postfix can’t send emails to other SMTP servers. Ask your ISP/hosting provider to open it for you. If they refuse your request, you need to set up SMTP relay to bypass port 25 blocking.

Still Can’t Send Email?

If port 25 (outbound) is not blocked, but you still can’t send emails from your own mail server to your other email address like Gmail, then you should check the mail log (/var/log/mail.log).

sudo nano /var/log/mail.log

For example, some folks might see the following lines in the file.

host[2404:6800:4003:c03::1b] said: 550-5.7.1 [2a0d:7c40:3000:b8b::2] Our system has detected that 550-5.7.1 this message does not meet IPv6 sending guidelines regarding PTR 550-5.7.1 records and authentication. Please review 550-5.7.1 for more information

This means your mail server is using IPv6 to send the email, but you didn’t set up IPv6 records. You should go to your DNS manager, set AAAA record for, then you should set PTR record for your IPv6 address, which is discussed in step 8.

Step 7: Using Mail Clients on Your Computer or Mobile Device

Fire up your desktop email client such as Mozilla Thunderbird and add a mail account.

  • In the incoming server section, select IMAP protocol, enter as the server name, choose port 143 and STARTTLS. Choose normal password as the authentication method.
  • In the outgoing section, select SMTP protocol, enter as the server name, choose port 587 and STARTTLS. Choose normal password as the authentication method.

ubuntu postfix dovecot letsencrypt https

You can also use IMAP on port 993 with SSL/TLS encryption.

Step 8: Improving Your Email Server Reputation

To prevent your emails from being flagged as spam, you should set PTR, SPF, DKIM and DMARC records.

PTR record

A pointer record, or PTR record, maps an IP address to an FQDN (fully qualified domain name). It’s the counterpart to the A record and is used for reverse DNS lookup, which can help with blocking spammers. Many SMTP servers reject emails if no PTR record is found for the sending server.

To check the PTR record for an IP address, run this command:

dig -x IP-address +short


host IP-address

PTR record isn’t managed by your domain registrar. It’s managed by the organization that gives you an IP address. Because you get IP address from your hosting provider or ISP, not from your domain registrar, so you must set PTR record for your IP in the control panel of your hosting provider or ask your ISP. Its value should be your mail server’s hostname: If your server uses IPv6 address, be sure to add a PTR record for your IPv6 address as well.

To edit the reverse DNS record for your Contabo VPS, log into Contabo control panel, then select Reverse DNS Management on the left sidebar and set the PTR record for your server’s IP address. The value of the PTR record should be set to your mail server’s hostname:

contabo PTR record

SPF Record

SPF (Sender Policy Framework) record specifies which hosts or IP address are allowed to send emails on behalf of a domain. You should allow only your own email server or your ISP’s server to send emails for your domain. In your DNS management interface, create a new TXT record like below.

modoboa spf record


  • TXT indicates this is a TXT record.
  • Enter @ in the name field to represent the main domain name.
  • v=spf1 indicates this is a SPF record and the version is SPF1.
  • mx means all hosts listed in the MX records are allowed to send emails for your domain and all other hosts are disallowed.
  • ~all indicates that emails from your domain should only come from hosts specified in the SPF record. Emails that are from other hosts will be flagged as forged.

To check if your SPF record is propagated to the public Internet, you can use the dig utility on your Linux machine like below:

dig txt

The txt option tells dig that we only want to query TXT records.

DKIM Record

DKIM (DomainKeys Identified Mail) uses a private key to digitally sign emails sent from your domain. Receiving SMTP servers verify the signature by using the public key, which is published in the DNS DKIM record.

When we were adding domain name in Moboboa admin panel earlier, we enabled DKIM signing, so the signing part is taken care of. The only thing left to do is creating DKIM record in DNS manager. First go to Modoboa admin panel as the admin user and select your domain name. In the DNS section, click Show key button.

modoboa dkim signing

The public key will be revealed. There are two formats. We only need the Bind/named format.

modoboa dkim public key

Go to your DNS manager, create a TXT record, enter modoboa._domainkey in the Name field. (Recall that we used modoboa as the selector when adding domain name in the admin panel.) Copy everything in the parentheses and paste into the value field. Delete all double quotes. Your DNS manager may require you to delete other invalid characters, such as carriage return.

modoboa dkim format

Note that your DKIM record may need sometime to propagate to the Internet. Depending on the domain registrar you use, your DNS record might be propagated instantly, or it might take up to 24 hours to propagate. You can go to, enter modoboa as the selector and enter your domain name to check DKIM record propagation.

For those who are interested, Modoboa uses OpenDKIM to generate private key for your domainkey and verify signatures of inbound emails.

DMARC Record

DMARC stands for Domain-based Message Authentication, Reporting and Conformance. DMARC can help receiving email servers to identify legitimate emails and prevent your domain name from being used by email spoofing.

To create a DMARC record, go to your DNS manager and add a TXT record. In the name field, enter _dmarc. In the value field, enter the following:

v=DMARC1; p=none; pct=100; rua=mailto:[email protected]

create dmarc record txt

The above DMARC record is a safe starting point. To see the full explanation of DMARC, please check the following article.

Step 9: Testing Email Score and Placement

After creating PTR, SPF, DKIM record, go to You will see a unique email address. Send an email from your domain to this address and then check your score. As you can see, I got a perfect score.

Testing-Email-Score-and-Placement can only show you a sender score. There’s another service called GlockApps that allow you to check if your email is placed in the recipient’s inbox or spam folder, or rejected outright. It supports many popular email providers like Gmail, Outlook, Hotmail, YahooMail, iCloud mail, etc


What if Your Emails Are Still Being Marked as Spam?

I have more tips for you in this article: How to stop your emails from being marked as spam. Although it requires some time and effort, your emails will eventually be placed in inbox after applying these tips.

What if Your Email is Rejected by Microsoft Mailbox?

Microsoft seems to be using an internal blacklist that blocks many legitimate IP addresses. If your emails are rejected by Outlook or Hotmail, you need to submit the sender information form. After that, your email will be accepted by Outlook/Hotmail.

Auto-Renew Let’s Encrypt TLS Certificate

Modoboa installed the latest version of Let’s Encrypt client (certbot) as /opt/certbot-auto. Let’s Encrypt TLS certificate is valid for 90 days. To automatically renew the certificate, edit root user’s crontab file.

sudo crontab -e

Add the following line at the end of this file.

@daily /opt/certbot-auto renew -q && systemctl reload nginx postfix dovecot

Save and close the file. This tells Cron to run the certbot renew command every day. If the certificate has 30 days left, certbot will renew it. It’s necessary to reload Nginx web server, Postfix SMTP server and Dovecot IMAP server so they can pick up the new certificate.

Enabling SMTPS Port 465

If you are going to use Microsoft Outlook client, then you need to enable SMTPS port 465 in Postfix SMTP server.


First, please use a VPS with at least 2GB RAM. Running Modoboa on a 1GB RAM VPS will cause the database, SpamAssassin, or ClamAV to be killed because of out-of-memory problem. If you really want to use a 1GB RAM VPS, you are going to lose incoming emails and have other undesirable outcomes.

If the Modoboa web interface isn’t accessible, like a 502 gateway error, you should check the Nginx logs in /var/log/nginx/ directory to find clues. You may also want to check the mail log /var/log/mail.log.

Check if the various services are running.

systemctl status postfix

systemctl status dovecot

systemctl status nginx

systemctl status mariadb

systemctl status clamav-daemon

systemctl status amavis

systemctl status uwsgi 

systemctl status supervisor

If you enabled the firewall, you should open the following ports in the firewall.

HTTP port:  80
HTTPS port: 443
SMTP port:  25
Submission port: 587 (and 465 if you are going to use Microsoft Outlook mail client)
IMAP port:  143 and 993

If you would like to use the UFW firewall, check my guide here: Getting started with UFW firewall on Debian and Ubuntu.

I found that the clamav-daemon service has a tendency to stop without clear reason even when there’s enough RAM. This will delay emails for 1 minute. We can configure it to automatically restart if it stops via the systemd service unit. Copy the original service unit file to the /etc/systemd/system/ directory.

sudo cp /lib/systemd/system/clamav-daemon.service /etc/systemd/system/clamav-daemon.service

Then edit the service unit file.

sudo nano /etc/systemd/system/clamav-daemon.service

Add the following two lines in the [service] section.


Like this:

ExecStart=/usr/sbin/clamd --foreground=true
# Reload the database
ExecReload=/bin/kill -USR2 $MAINPID

Save and close the file. Then reload systemd and restart clamav-daemon.service.

sudo systemctl daemon-reload
sudo systemctl restart clamav-daemon

(Optional) Set Up Autodiscover and AutoConfig to Automate Mail Client Configuration

Autodiscover and AutoConfig make it easy to configure a desktop or mobile mail client. The end user just need to enter a name, email address and password to set up his/her mail account, without having to enter the SMTP or IMAP server details. Autodiscover is supported by Microsoft Outlook mail client and AutoConfig is supported by Mozilla Thunderbird mail client.

Modoboa uses AutoMX to implement this feature on your mail server. All we need to do now is add CNAME records in DNS. In your DNS manager, create two CNAME records.       CNAME     CNAME

Go to the Domains tab in your Modoboa admin panel, if the autoconfig is in green, that means your CNAME records are correct. (Modoboa checks DNS records for your mail server every 30 minutes, so you might need to wait some time for autoconfig to turn green.)

modoboa automx

Once the CNAME records are propagated to Internet, you don’t have to enter the SMTP or IMAP server details when setting up mail account in Microsoft Outlook and Mozilla Thunderbird.

Host Multiple Domains in Modoboa

See the following article:

Wrapping Up

I hope this tutorial helped you set up a mail server on Debian 10 Buster with Modoboa. As always, if you found this post useful, then subscribe to our free newsletter to get more tips and tricks. Take care 🙂

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22 Responses to “How to Quickly Set Up a Mail Server on Debian 10 Buster With Modoboa

  • I mentioned this in the article, but I want to say it again: The best practice to run Modoboa is using a clean fresh OS.

    Generally speaking, if there’s a script that will install lots of software, it’s a good practice to install it on a clean freash OS. Otherwise, the install script might mess up the existing configurations of your software, making it unusable. Or maybe a component of the softwar stack needs to bind to a port, but it’s already been taken by an existing process on the server, resulting in installation failure.

    Unless you are very knowledgeable about every piece of software on the server and can spead lots of time debugging, it’s not recommended to install Modoboa on a server that has other applications running.

    I have seen many folks who didn’t follow this advice bork the applications on their servers.

  • Amavis and ClamAV use about 1.3GB RAM. If your server doesn’t have enough RAM, you might not be able to receive emails. If you don’t need AntiVirus on your mail server, you can disable Amavis and ClamAV. This will save you 1.3GB RAM.

    Edit Postfix master configuration file.

    sudo nano /etc/postfix/

    Find the following lines in this file and comment them out.

    -o smtpd_proxy_filter=inet:[]:10024
    -o smtpd_proxy_options=speed_adjust
    -o milter_macro_daemon_name=ORIGINATING
    -o smtpd_proxy_filter=inet:[]:10026

    Save and close the file. Then restart Postfix.

    sudo systemctl restart postfix

    Now you can stop Amavis and ClamAV.

    sudo systemctl stop amavis clamav-daemon

    And disable auto-start at boot time.

    sudo systemctl disable amavis clamav-daemon
  • Adnan Batara
    6 months ago

    Hello Xiao Guoan,

    Have you tried setting up Modoboa to use LDAP authentication instead of SQL database and RoundCube webmail interface?

    Look forward to hearing from you soon.

    Thanks and best regards.

  • Samuel BARRET
    5 months ago

    I think I’ve followed everything as it should be but I can’t send an email

    Nov 30 08:52:19 vmi483626 postfix/smtpd[3381]: warning: connect to Connection refused
    Nov 30 08:52:19 vmi483626 postfix/smtpd[3381]: warning: problem talking to server Connection refused
    Nov 30 08:52:20 vmi483626 postfix/smtpd[3381]: warning: connect to Connection refused
    Nov 30 08:52:20 vmi483626 postfix/smtpd[3381]: warning: problem talking to server Connection refused

    • Port 9999 is used by the Modoboa policy daemon. Edit the Modoboa settings file.

      sudo nano /srv/modoboa/instance/instance/

      Make sure you have modoboa.policyd in MODOBOA_APPS.

      MODOBOA_APPS = (
          # Modoboa extensions here.

      Save and close the file. Then restart supervisor.service for the changes to take effect.

      sudo systemctl restart supervisor.service

      To check if the policy daemon is running, use this command.

      sudo ss -lnpt | grep 9999

      If it’s running, you would see a line like

      LISTEN    0         100       *        users:(("python",pid=9463,fd=8)) 

      If it’s not running, you can check the supervisor log.

      sudo journalctl -eu supervisor.service
      • Samuel BARRET
        5 months ago

        When I make this order nothing happens

        pre>sudo ss -lnpt | grep 9999

        My file is correct

        > modoboa.policyd in MODOBOA_APPS

    • Is there any error message in the log?

      sudo journalctl -eu supervisor.service
      • Samuel BARRET
        5 months ago

        I have reinstalled everything from 0 and now I have an error 502

        error log nginx

        *1 upstream prematurely closed connection while reading response header from upstream, client: my_public_ip, server:, request: "GET /favicon.ico HTTP/1.1", upstream: "uwsgi://unix:/run/uwsgi/app/modoboa_instance/socket:", host: "", referrer: ""
    • How many RAM does you server have and is the uwsgi service running?

      sudo systemctl status uwsgi
  • Alessandro
    3 months ago

    Modoboa notify me that a new release is available. How to update an existing installation?
    I searched online but I don’t find simple guides like yours!
    Thank you!

  • I have been using this for some time now as SMTP after installation and been working perfectly fine.
    For two days now I’ve been trying to do installation on three different servers but none worked as SMTP but worked fine as webmail.
    Below is the error message I get when I try to use as SMTP.

    Error in processing. The server response was: 4.3.5
    : Recipient address rejected:
    Server configuration problem

    NB: [email protected] is a live email

  • Excellent tutorial.

    Where are the mailbox located and how can I move them to another directory?

  • Drygord
    1 month ago


    I did a fresh install and followed your guide to the letter.

    Modoboa web panel was working through https- with valid SSL certificates. Then suddenly I got to the domain/ / “mailboxes” step and I received a security warning.

    I tried to bypass it manually and got a bad certificate: 400 error. The details listed a bunch of other sites that the letsencrypt certificate was valid for but not mine.

    I tried a couple more times then suddenly all of my website was giving bad certificate errors, or just resolving to my domain registrar.

    What I don’t understand is why the mailboxes section in particular had this issue and why it spread to the rest of the domain? Or could this be some strange issue with DNS propagation that will resolve in time?


    • Are you using Cloudflare DNS?

      You need to disable Cloudflare proxy for the hostname of your mail server permanently, otherwise you won’t be able to receive emails, because Cloudflare doesn’t support SMTP and IMAP proxy. There’s no way around it.

      To disable Cloudflare for a hostname, click the orange cloud icon under the Proxy status column in the DNS dashboard. Then another orange cloud icon will appear. Click on it, the status will change to DNS only. Save the setting, and you are done.

  • Wayne Oliver
    1 month ago

    Fresh Debian 10 install and this breaks bad,
    Internal server error.

  • Rodrigo
    3 weeks ago
    systemctl status clamav-daemon
    ● clamav-daemon.service - Clam AntiVirus userspace daemon
       Loaded: loaded (/etc/systemd/system/clamav-daemon.service; enabled; vendor preset: enabled)
      Drop-In: /etc/systemd/system/clamav-daemon.service.d
       Active: active (running) since Fri 2021-04-16 23:57:23 UTC; 3s ago
         Docs: man:clamd(8)
      Process: 11077 ExecStartPre=/bin/mkdir /run/clamav (code=exited, status=1/FAILURE)
      Process: 11078 ExecStartPre=/bin/chown clamav /run/clamav (code=exited, status=0/SUCCESS)
     Main PID: 11079 (clamd)
        Tasks: 1 (limit: 2358)
       Memory: 322.0M
       CGroup: /system.slice/clamav-daemon.service
               └─11079 /usr/sbin/clamd --foreground=true

    Whats is this? “(code=exited, status=1/FAILURE)”
    Success ou Fail?

  • Rodrigo
    3 weeks ago

    What is this?
    My mail server send but not receive emails:

    host[x.x.x.x] said: 550 5.1.1
        : Recipient address rejected: undeliverable address:
        mail for loops back to myself (in reply to RCPT TO command)

    Can you help me, please?

  • Rodrigo
    3 weeks ago

    sudo nano /etc/postfix/

    You forget to explain that the postfix need to be configured:

    myhostname =
    myorigin =
    mydestination = $myhostname, localhost.$mydomain, localhost

    The default configuration of the installation leaves the hostname the same as the origin, and ends up giving a problem in receiving and sending email.

  • Rodrigo
    2 weeks ago

    opendkim.service: Can’t open PID file /run/opendkim/ (yet?) after start: No such file or directory

    DKIM not working in my installation

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