Thank you Stan. I didn't notice this button.
At the bottom of the message is a link titled “mute this topic”. Click on it and it will take you to the groups.io page where you can mute the topic.
View/Reply Online (#120347) | Reply to Group | Reply to Sender | Mute This Topic? | New Topic Your Subscription | Contact Group Owner | Unsubscribe [pierreraymondrondelle@...]
Your Subscription | Contact Group Owner | Unsubscribe [pierreraymondrondelle@...]