Hello @Bob Dayvault
Testing Word in Safe Mode is a good next step here. Since the Mailings tab itself isn't responding, troubleshoot Word first rather than the printer or envelope settings.
Close Word completely, press Windows + R, and run:
winword /safe
Then open a blank document and try Mailings → Envelopes again. Office Safe Mode helps identify problems caused by add-ins or extensions.
If Mailings → Envelopes works in Safe Mode, an add-in is a likely cause. Restart Word normally and go to File → Options → Add-ins. At the bottom, select COM Add-ins → Go, temporarily disable the add-ins, and test again. Then re-enable them one at a time to identify the one causing the problem.
If the Mailings tab is still unresponsive even in Safe Mode, next, update Office through File → Account → Update Options → Update Now, then try an Office repair. Start with Quick Repair; if that doesn't resolve it, use Online Repair. Both repair options are for Microsoft 365/Office applications that aren't functioning correctly.
Once the Mailings controls are responding normally, the standard envelope workflow is Mailings → Envelopes → Options → Printing Options. Word gets envelope feed information from the printer driver, so if the dialog opens normally but the envelope then fails to print, I would move on to the printer driver, envelope size, and feed configuration.
If Safe Mode doesn't help, please share your Word version/build and Windows version, and whether the entire Mailings ribbon is unresponsive or only Envelopes/Labels. That will help narrow this down further.
References:
Open Office apps in Safe Mode
Create and print a single envelope in Word
Repair an Office application
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