---
type: concept
title: Blocked Email Attachments
tags: [security, email, malware-prevention]
related: [email-spam-virus-protection]
created: 2026-06-30
updated: 2026-06-30
sources: ["output/rz_uni_greifswald_de_dienste_allgemein_e_mail_spam_virenschutz_uebersicht_gesper.md"]
---

# Blocked Email Attachments

The **Blocked Email Attachments** policy is a security measure implemented by the [[universitatsrechenzentrum-urz]] to prevent the spread of malware, ransomware, and unauthorized scripts via the university's central email service.

## Enforcement Mechanism
The filtering occurs in **real-time**. If an incoming email contains any of the prohibited file extensions, the email is rejected at the gateway. The sender is notified immediately of the failure, and the email never reaches the recipient's mailbox.

## Prohibited File Types

| Category | Extensions |
|---|---|
| **Windows Executables & Installers** | `.exe`, `.exe-ms`, `.com`, `.msi`, `.msp`, `.mst`, `.scr` |
| **macOS Applications** | `.app` |
| **Scripts & Command Files** | `.bat`, `.cmd`, `.vbs`, `.vbe`, `.js`, `.jse`, `.bas`, `.sct`, `.wsc`, `.wsf`, `.wsh` |
| **Microsoft Access** | `.ade`, `.adp`, `.mda`, `.mdb`, `.mde`, `.mdw`, `.mdt`, `.mdz` |
| **Legacy Office (Office 2000)** | `.doc`, `.ppt`, `.xls` |
| **System & Registry** | `.reg`, `.inf`, `.cpl`, `.msc`, `.lnk`, `.shb` |
| **Binary & Encoded Data** | `.b64`, `.bhx`, `.hqx`, `.uu`, `.uue`, `.xxe` |
| **Other/Miscellaneous** | `.chm`, `.hlp`, `.hta`, `.ins`, `.isp`, `.emf`, `.wmf`, `.fxp`, `.grp`, `.mim`, `.pcd`, `.prg` |

## Implications
- **Modern Office Formats**: Because only the legacy formats (`.doc`, `.xls`, `.ppt`) are explicitly listed as blocked, modern XML-based formats (e.g., `.docx`, `.xlsx`, `.pptx`) are generally permitted.
- **Troubleshooting**: If a legitimate file is blocked, the sender will receive an automated notification. Users requiring these files may need to use alternative transfer methods such as [[nextcloud]].