An add-in shown in an installer list is not necessarily the same library version loaded by a running application. For a classic Outlook problem, recording the actual loaded DLLs can give the software supplier a more precise starting point.

This procedure applies to desktop Outlook using OUTLOOK.EXE, including the versions named in Microsoft's guide. It is not a procedure for the new Outlook app or Outlook in a browser. Use an authorised Windows 11 session and obtain Process Explorer from Microsoft's Sysinternals page.

Capture the running application's libraries

Start classic Outlook and bring it to the state where the relevant add-in is normally used. Avoid exposing private messages while collecting the evidence. In Process Explorer, search for outlook.exe and select the appropriate OUTLOOK.EXE process.

Choose View, Show Lower Pane, then View, Lower Pane View, DLLs. In the lower pane, right-click a column heading and use Select Columns, DLL, Version to show version information.

Microsoft documents File, Save As, Save for exporting this lower-pane data as tab-delimited text. Save it to a private diagnostic folder with a name identifying the capture time. Confirm the exported headings include the information needed, such as name, company, path and version.

Process Explorer's DLL view concerns libraries and mapped files loaded by the selected process. Selecting another process changes what the lower pane represents, so preserve that context with the export.

Compare evidence without treating a library as the culprit

Match the relevant paths and versions with the add-in vendor's supported installation details. An unfamiliar company name or a blank company field is a reason to investigate, not proof of malware or the cause of the Outlook failure.

Keep the original export before filtering a working copy. Include the exact symptom and whether Outlook had been restarted after an update. Do not delete a DLL from its folder or force-close handles as an experiment.

After any separately agreed add-in repair, repeat the same capture conditions and compare the specific loaded entry. Also test the original Outlook task. A changed version number confirms a different loaded library; only the task test shows whether the user's problem was resolved.

Sources: Microsoft Outlook loaded-DLL procedure; Microsoft Process Explorer.