Microsoft 365 / Azure

Where Do SPF, DKIM, and DMARC Apply? — Understanding All Three Through the Flow of a Single Email

We break down the roles of SPF, DKIM, and DMARC through the lifecycle of a single email. Based on the 2026 DMARC standard RFC 9989, we also review differences from the older RFC 7489.
2026.09.08
Microsoft 365 / Azure
VBA / Office

Dictionary is Convenient for Counting Duplicates in VBA — Aggregate Securely Without References

Use Scripting.Dictionary with Late Binding to aggregate duplicate values in column A. Output results to a dedicated sheet to prevent accidental deletion of input data.
2026.09.08
VBA / Office
Networking / RFC

In Which Layer Do HTTP 404, 502, and 504 Occur? — Troubleshooting from the Nginx and Application Request Path

Review the HTTP meanings of 404, 502, and 504 based on RFC 9110, and organize where to start investigating across Nginx and upstream applications along the request path.
2026.09.08
Networking / RFC
Linux / CLI / DevOps

What to Check Before Changing Nginx Configuration? — Using nginx -t and nginx -T Properly

This article outlines a safe sequence for testing configurations with nginx -t before reloading Nginx, and using nginx -T to inspect the entire loaded configuration only when necessary.
2026.09.08
Linux / CLI / DevOps
VBA / Office

Bulk Delete Empty Rows in Excel — Safely Cleaning Only the Target Table with Office Scripts

Using Office Scripts to delete only completely empty rows in a specified Excel table from the bottom up. When multiple tables exist, the target name must be specified to make it harder to accidentally modify other tables.
2026.09.08
VBA / Office
AI & Machine Learning

How Do Filter Bubbles Form? — Running a Simple Model of “Narrowing Recommendations” in PowerShell

We explore the concept of filter bubbles through an educational model in PowerShell consisting of recommendation -> click -> interest estimate update -> candidate reduction.
2026.09.07
AI & Machine Learning
VBA / Office

Saving UTF-8 Without Garbled Characters in VBA — Using ADODB.Stream Without Reference Settings

Call ADODB.Stream from VBA using Late Binding to save UTF-8 BOM-included text to a file. We also organize where and when to use Charset.
2026.09.07
VBA / Office
PowerShell

Catching the Exact Moment a File Arrives in a Folder — Change Monitoring with PowerShell + FileSystemWatcher

Use the .NET FileSystemWatcher from PowerShell to monitor creations, modifications, deletions, and renames in a folder as events.
2026.09.07
PowerShell
Security

Do Not Put Secret Strings in Plaintext Files ― Calling Windows DPAPI from PowerShell

A minimal example of using .NET's ProtectedData from Windows PowerShell 5.1 to encrypt a secret string for the current user and save it to a file.
2026.09.07
Security
Microsoft 365 / Azure

Clean Up Leading/Trailing and Full-Width Spaces in Excel: Fixing Inconsistencies with Office Scripts

Use Office Scripts to format only string values within an Excel table by cleaning up leading and trailing spaces, full-width spaces, and consecutive spaces while skipping formula cells.
2026.09.07
Microsoft 365 / Azure
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