Why can't I sign in or getting "Not Authenticated" when I start MailMerge365?

If you start MailMerge365 and receive an error stating "Not Authenticated" this happens mostly with browsers or browser plugin that have strict cookie settings. This affects most Office plugins and add-ins when using Outlook for the Web (not just MailMerge365). 

How to fix in general? See below for specific browsers.

  • Try a different browser or use incognito mode (also called private browsing in some browsers) in your preferred browser. 
  • Try disabling plugins (e.g. Privacy Enhancers, Privacy Blockers, Anti-Virus) may help or for some plugins you can select the option "Trust this site" or "Allow site" while visiting the Outlook website. If you try this we recommend going into incognito mode and then deactivating the plugins one by one, then refreshing the page to see the effect. This lets you identify which plugin was causing the issue and perform a fix outside of the incognito window (using your normal browsing window). 
  • Turn off third-party cookie blocking as described here: https://support.panopto.com/s/article/How-to-Enable-Third-Party-Cookies-in-Supported-Browsers


If you are using Chrome first click on the 3rd party cookie menu and then click allow


Due to changes in detection of third party cookies Safari may block our authentication cookie. If you are experiencing this issue please first visit https://app.mailmerge365.com in Safari and log-in there. This will signal to Safari to trust our authentication cookie. After thatYou can then use the plugin as you would normally.


In your browser go to Outlook in Microsoft 365 (aka Office365). Locate the Lion icon on your toolbar (top right) and click on it. In the popup there is a dropdown that reads "Cross-site cookies blocked". Open the dropdown and select "All cookies allowed" to use MailMerge365. 

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