Marv,
10% are bouncing. That is more troubling.
Not necessarily. Y!Groups bounce tracking has had problems for several years, and these may be addresses which should have been listed as Bouncing at Y!Groups, but for one reason or another weren't.
I posted on the Y! group that members should be receiving posts from
groups.io and to adjust their anti-spam if they are not.
And particularly if their email service uses a "challenge" type of anti-spam they may need to explicitly white-list groups.io.
Shal
Shal Farley