hughmoz said

Thunderbird used to show when new emails came into my Mac on the icon on the dock, but no longer does this.

Hello hughmoz,

Just to make sure; would you please check your settings as described in this article :

https://www.lifewire.com/new-email-alerts-thunderbird-1173081

It does work thanks with information on the link that you kindly supplied, but takes a lot of minutes to show on the icon on the dock on my Mac. On my iPhone they show up very quickly after sending so, there is delay problem on my Mac which is unacceptable. If I click on the Thunderbird icon on the dock the emails are already on my Mac, however, the number of emails notifications take several minutes to show on the dock. It seems that every time one updates Thunderbird one loses features that were instantaneous in earlier versions. :)