Common Definitions


This page contains some common definitions which will be used through the guide in several places. Note, that this section is most important as errors from this document will propagate through the whole guide and may cause different major problems, which will be difficult to solve.

First of all, we need to create a specific user for all mail processing. For security reasons and to get dovecot running as the local delivery agent (LDA) for postfix later, we are not allowed to use the postfix user id! Our dedicated system mail user is created as follows.

sudo adduser --system -ingroup mail vmail

The command creates the user vmail, adds it to the group mail and prints out the user id and group id of the newly created user. For the scope of this document, the values are as follows.

uid=118(vmail) gid=8(mail)

Note, that your ids might differ from above and you will need to substitute above values by yours whenever noted in the text. Do not forget to add your postfix user to the mail group as well! Otherwise you will get into access problems with the SASL socket!
The server hostname used in this document is

As a general note: in case of odd things happening, you should go for the mailer logfiles, especially for /var/log/ - e. g. by using the following command.

sudo tail -f /var/log/

Now, you can forward to the actual mail server installation.
Cheers, iss.