Postfix System Technician

We are looking for an experienced System Technician with strong expertise in Postfix and Linux to implement and support a Sender Rewriting Scheme (SRS) solution in an existing email environment. The assignment may include operation and maintenance of Postfix servers, but the primary focus will be implementing Sender Rewriting Scheme (SRS) to support an email flow where incoming email is received for internal users and then forwarded to external email services such as Gmail or Outlook.com. Assignment Overview The SRS solution will be implemented in an existing Postfix environment and should only apply to emails that:

• Have passed the spam filter.
• Are identified as being forwarded to an external email server.

The Postfix servers perform address lookups against a custom-developed LDAP directory, not Active Directory. The directory contains users' email addresses and determines where an incoming message should be delivered. Only after this lookup can Postfix determine whether the message should be delivered locally to Exchange or forwarded to an external recipient. Postfix server configuration is managed using SaltStack. A test environment is available for development, verification, and testing of the solution. Responsibilities The consultant will:

• Analyze the existing email flow and identify an appropriate design for SRS.
• Design and implement an SRS solution in Postfix.
• Ensure that address rewriting is only applied to forwarded emails sent to external recipients.
• Verify that local delivery to Exchange is not affected.
• Document the solution and any configuration changes.
• Support troubleshooting and, where applicable, operation and maintenance of the Postfix environment.

Mandatory Requirements

• Competence Level 3, corresponding to 4 to 8 years of experience.
• Academic education in a relevant field or equivalent professional experience considered equivalent by the client.
• Several years of solid experience as a System Technician working with Postfix in Linux environments.
• Experience implementing and troubleshooting SRS.
• Network knowledge related to SMTP traffic routing, including:
• DKIM
• DMARC
• SPF
• Experience with LDAP integrations in email environments.
• Strong problem-solving skills with an analytical and structured approach.
• Good spoken and written Swedish and English.
• Experience from at least two assignments of similar nature, scope, and complexity involving operation, implementation, maintenance, or troubleshooting of Postfix-based email solutions in Linux environments.

Preferred Requirements

• Experience with configuration management using SaltStack or an equivalent tool.
• Experience with troubleshooting tools in Linux environments, such as:
• strace
• tcpdump
• bpftrace
• Experience with IT operations and maintenance within the public sector, using a delivery model aligned with agile product management.
• Strong understanding of IT security and the ability to work accordingly.
• Ability to substantiate information provided in the CV during the interview.
• Ability to explain the reference assignments submitted and how the experience gained from them is relevant to the current assignment.

Working Arrangement Remote work: Remote work may be permitted for up to 2 days per week. Extension Location: Stockholm Option: 6-month extension