All articles · Page 3
When the log fills the disk: properly limiting log4j2 RollingFile, using totemomail as an example
A log volume filling up can bring down the entire gateway in the worst case. Why combining time- and size-based rotation without %i creates a single huge file, how strategy.max caps retention, the role of the log level, and where totemomail hides these values.
How Long Does an SMTP Session Stay Open? ConnectionTimeout 00:10:00 in Exchange and the Systems for Which That Is Too Short
Exchange terminates every incoming SMTP session after ten minutes, even if it is currently transferring data. Which senders stay on a connection that long, how to determine the actual session duration from the protocol log, and when ConnectionTimeout and ConnectionInactivityTimeout should be adjusted on a relay connector.
New Outlook: S/MIME signature cannot be verified in secondary account, attachments missing
The new Outlook reports that the S/MIME signature cannot be verified in a secondary account for a shared mailbox and does not display attachments. This article explains the difference between Clear Signing and Opaque Signing, why attachments disappear from opaque-signed messages, why the new Outlook processes S/MIME only in the primary account, and what workarounds are available, including unpacking smime.p7m with PowerShell or OpenSSL.
Port Forwarding with netsh portproxy: Access Internal Services Through a Jump Host
Windows includes built-in TCP port forwarding with netsh interface portproxy. Combined with a VPN such as Tailscale, it lets you access an internal service, such as a NAS interface, from outside without exposing it publicly. Learn how to set up, secure, and remove forwarding, and where its limitations lie: no UDP, no additional encryption, and certificate and redirect pitfalls.
Tailscale: Exit Nodes and Subnet Routes Compared, and How They Work Technically
In Tailscale, exit nodes and subnet routers are two related but distinct operating modes. A subnet router selectively opens specific IP ranges, while an exit node routes all internet traffic through itself. What the difference means in practice, how Tailscale implements it through WireGuard, route approval, and SNAT, and where the limits of each option lie.
Prerequisites for Remote PowerShell to Work
PowerShell remoting rarely fails because of the command itself, but rather because of prerequisites: the WinRM service, listener, firewall, authentication, and the specifics of local accounts. What needs to be configured on the target and client sides, how to check it with Test-WSMan, and why Access denied usually has nothing to do with the password.
RustDesk: Setting Up the Open-Source TeamViewer Alternative
RustDesk is open-source remote support software licensed under the AGPL, free of charge and self-hostable. Learn how to install the client on Windows (including unattended deployment via MSI), how connections work through the public rendezvous server, your own server, or a direct connection, which features are needed for day-to-day support, and where the limits of free use lie.
CVE-2026-62911: Why 85 Percent of On-Premises Exchange Servers Are Vulnerable and What Is Technically Behind It
The BSI reports that around 85 percent of on-premises Exchange servers in Germany are vulnerable to CVE-2026-62911. This article explains the vulnerability technically: MRSProxy, missing Channel Binding, NTLM relay, and Orange Tsai’s Pwn2Own chain, along with context for the figures and the specific recommended actions.
Essential Controls for TotemoMail Admins: Stop the Server, Check Queues, and Clean Up in a Controlled Manner
The key controls for operating a totemomail gateway: stop the service via systemd and the Tanuki control script, count queue contents per repository, inspect individual messages, clean up in a controlled manner, and restart the service.
NDR, DSN, Bounce: How to correctly distinguish non-delivery notifications
NDR, DSN, bounce, reject, backscatter: The terms surrounding failed delivery are often used interchangeably, but they refer to different things. What the RFCs define, who generates which notification, how a DSN is structured, and why the distinction between reject and bounce determines backscatter.
Passwordless Linux Server Access: Set Up SSH Key Login with PuTTY, Pageant, and More
Admins who access Linux servers daily have to enter a username and password every time when using password login. An SSH key pair reduces this to a double-click: generate a key with PuTTYgen, store the public key on the server, and load Pageant. The same key works in WinSCP, MobaXterm, and OpenSSH, and if desired, takes you straight to a service account shell.
Sending mail through a relay: Checking TLS and authentication
A one-pager for Application Managers whose applications send mail through a relay: Which three application settings matter (port, TLS mode, authentication), what the options are called in common environments, and how a single test email’s Received header proves that the connection is actually encrypted and authenticated.
