Creating new users

Creating new mail users is not straightforward with our setup, and while instructions are given in the rest of this tutorial, they are spread over multiple different pages. This page attempts to collect all the instructions for creating a new mail user in one place; for administration of your mail server long after you have set it up.

Creating a new system user

Each mail user must have a corresponding system user; this is created using the commands:

sudo useradd -m <username>
sudo usermod -L <username>

Users created with these commands will have a home directory to store their mailbox in Maildir format, but cannot login on the mail server. Preventing login ensures that users cannot access and edit their own mails on the server, thus corrupting dovecot state.

Creating a password

The new mail user needs a password to send mail and access their mailbox. This can be setup by running the following command:

printf "<mail-username>:`doveadm pw -s BLF-CRYPT -p '<password>'`\n" | sudo tee -a /usr/local/etc/passwd.replica

which uses the doveadm tool to convert a given password to a stored format according to the specified scheme (in this case Blowfish crypt or BLF-CRYPT), and then stores the <mail-username>:<password> pair in the specified passwd-file (in this case /usr/local/etc/passwd.replica).

Make sure that you select a strong password.

For more information on using doveadm pw see here.

Creating additional recipients

By default, a new mail user with username <mail-username> will receive mail at <mail-username>@<domain-name>. However, you may wish to add additional recipients for the user.

This can be done by adding lines to /etc/aliases in the form:

<recipient>: <mail-username>

For example if you want a newly created mail user suline to also receive male sent to wife@<domain-name> in their mailbox, you would add a line

wife: suline

Configuring sender addresses

A mail user must also be configured with email addresses that it is allowed to send mail from. This configuration is managed in the file /etc/postfix/sender_login.

There is one line for each email address and each mail user such that the mail user is allowed to send mail from that email address, in the following format:

<email-address> <mail-username>

It is usual to add at least the email address <mail-username>@<domain-name> to this file for new mail users. So for example for a new mail user suline, add

suline@<domain-name> suline

to allow suline to send mail from suline@<domain-name>.

postfix uses an indexed version of this file, which must be updated using

sudo postmap hash:/etc/postfix/sender_login

Reload postfix to ensure these changes take effect:

sudo service postfix reload