Hi DonB, do you mean this add-on:

https://addons.mozilla.org/firefox/addon/gmail-checker-manager/

I can't tell whether it has a feature to change the interval between checks from 60 seconds to something else.

You could take a look at some of the other ones that have been around longer:

https://addons.mozilla.org/firefox/addon/gmail-notifier-restartless/

https://addons.mozilla.org/en-US/firefox/addon/gmail-checker-simple/

https://addons.mozilla.org/en-US/firefox/addon/checker-plus-gmail/

Those all only request permission to Gmail and not "all sites". I generally prefer extensions that require the fewest permissions.

Dear jsher2000, Thank you for your response but maybe I didn't make my question clear. I am not trying to adjust the INTERVAL between Gmail checks for incoming emails but how long the display notification time lasts when the incoming email is displayed on the desktop. When I was using the Chrome browser as my default browser, it was a simple adjustment in the Gmail Checker but in Firefox, I don't see this adjustment. Maybe I'm just screwed up. Best, Don

Oh, I see. But my answer would be the same: if that extension doesn't have what you're looking for, try another one.

I don't now of any other extension that will provide me with the notification that gmail checker does. I think the problem is on my end and I will research it further. Best, DonB

Oh, that's why I gave you the three links to other extensions. Let us know what you find out.