[Evolution] Mail arrival notifications -- turning off sound

[Anonymous Japhering <japhering gmail com>]

Evolution  3.40.1 (flatpak git5df1718) 

Linux Mint  19.3

Linux  5.4.0-70-generic #78~18.04.1-Ubuntu SMP  x86_64

I had a situation today where I had to turn the sound on for my primary computer.   Normally I run

with all sounds muted at hardware level.

For years, I've paid attention to the popup from Evolution which give a synopsis of the incoming message.  What

I wasn't aware of,  was the accompanying audio notification.   

So the question is ... How does one turn off the audio notification and leave the visual notification?   

I don't see any related to either in the documentation, although I  don't really know what I should be looking for.

Thanks.