Questions and answers

1. E-Mail services


How can you check whether it is possible to reach a certain SMTP server?

Use telnet SMTP-server 25 and wait for a connected response.

SMTP session using a telnet connection


Postfix uses two configuration files: and master.postfix. Correct?

No, those files are: and



Which parameter does Postfix use in order to learn for which domain(s) to receive mail?

The parameter to be used is mydestination. Multiple domainnames can be seperated using a whitespace, a comma or both.

Configuring Postfix


What is the purpose of using virtual domains?

In order to configure Postfix to handle mail for additional domains besides its own virtual hosts can be added.

Virtual Domains


What is procmail?

Procmail is a mail filtering utility and is used for pre-processing and sorting incoming mail.



How would you get an overview of all flags that procmail recognizes?

procmail -h.


What does the bang character (!) mean at the beginning of the last line of a recipe?

It means that the message that matches the previous condition(s) has to be forwarded to another mailbox.


Why is it necessary with Courier to create system aliases?

Courier does not deliver mail to root (for security reasons) and therefore system aliases (at least for root) need to be created.


Which is the most common way to implement authentication for Dovecot?

The most common way is using PAM authentication.

Dovecot authentication


Why would you configure and limit the use of the index files using mbox_min_index_size when using Dovecot as a POP3 server?

This is a workaround in order to get updated on deleted mail messages when using mbox instead of maildir.

Dovecot POP3 server

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