KBM 10 Telefon- und E-Mail-Kommunikation (EN)

KBM 10 Telephone and Email Communication

In this module, you will learn the fundamentals of professional telephone and email communication for the business sector. You will gain insights into the technical infrastructure of modern email communication and learn how to send and receive emails securely, efficiently, and in accordance with common standards. The focus is on practical applications and technical concepts that are relevant for the administration of email systems in companies.

Concepts and Background

Mailcow

A comprehensive, open-source email communication package based on Docker containers that combines all necessary services for a full-fledged mail server.

Postfix

A widely used, secure, and flexible Mail Transfer Agent (MTA) responsible for receiving and forwarding emails and serving as a central component in Mailcow.

Dovecot

An IMAP and POP3 server that enables access to email mailboxes through various clients and is responsible for the secure storage and management of emails.

DKIM, DMARC, SPF

Three central security standards for email authentication: SPF (Sender Policy Framework) authorizes sending servers, DKIM (DomainKeys Identified Mail) digitally signs emails, and DMARC (Domain-based Message Authentication, Reporting & Conformance) combines both and gives receiving policies for handling unauthenticated emails.

Spamassassin

A filtering program that analyzes emails for spam characteristics and assigns a score to identify and block unwanted messages.

Architecture Diagram

flowchart LR
  A[Internet] --> B(Firewall)
  B --> C[Mailcow-Server]
  C --> D[Postfix]
  C --> E[Dovecot]
  C --> F[Spamassassin]
  D --> G[DKIM/SPF/DMARC]
  E --> H[Roundcube]

Practical Steps

1. Install Mailcow on a dedicated server with Docker and Docker Compose. This ensures that all components are correctly configured and run isolated from each other.
2. Configure SPF, DKIM, and DMARC records for your domain in the DNS management area of your domain registrar. This improves the deliverability of your emails and reduces spam.
3. Create new domains and user accounts in the Mailcow interface. Ensure that quotas for mailboxes are set appropriately to manage storage space.
4. Configure Spamassassin in the Mailcow interface by adjusting filter strength and making whitelist and blacklist entries for known senders.
5. Install and configure Roundcube as a webmail client to enable browser-based access to email accounts. Customize the theme and extensions as needed.
6. Test the functionality of the email system by sending and receiving test emails between different accounts to ensure that all components work together correctly.

Common Pitfalls

Further Resources

• Official Mailcow Documentation
• Postfix Documentation
• Dovecot Configuration Handbook
• Spamassassin Documentation
• Roundcube Configuration Guide

Knowledge Check

Four questions for self-assessment. Click on each question to see the correct answer and explanation.

Which component is primarily responsible for receiving and forwarding emails in a Mailcow environment?

• A) Dovecot
• B) Postfix
• C) Spamassassin
• D) Roundcube

Correct Answer: B. Postfix is the Mail Transfer Agent (MTA) responsible for receiving and forwarding emails. Dovecot is responsible for accessing mailboxes, Spamassassin for spam filtering, and Roundcube for the webmail interface.

Which security standard combines SPF and DKIM and gives receiving servers policies for handling unauthenticated emails?

• A) SPF
• B) DKIM
• C) DMARC
• D) TLS

Correct Answer: C. DMARC (Domain-based Message Authentication, Reporting & Conformance) combines SPF and DKIM and gives receiving servers policies for handling unauthenticated emails. SPF authorizes sending servers, DKIM digitally signs emails, and TLS is a protocol for secure data transmission.

Which service enables access to email mailboxes through various clients and is responsible for the secure storage of emails?

• A) Postfix
• B) Mailcow
• C) Dovecot
• D) Spamassassin

Correct Answer: C. Dovecot is an IMAP and POP3 server that enables access to email mailboxes through various clients and is responsible for the secure storage and management of emails. Postfix is responsible for mail transfer, Mailcow is the comprehensive package, and Spamassassin is responsible for spam filtering.

Which filtering program analyzes emails for spam characteristics and assigns a score to identify unwanted messages?

• A) Postfix
• B) Dovecot
• C) Spamassassin
• D) DKIM

Correct Answer: C. Spamassassin is a filtering program that analyzes emails for spam characteristics and assigns a score to identify and block unwanted messages. Postfix is for mail transfer, Dovecot for mailbox access, and DKIM for email signing.