First, if you receive a bounce probe message and activate the "unbounce"
link, rest assured that does work.  I thought that Groups.io sent an
automated response back confirming you are unbounced, but if they do not,
PLEASE, please, please assume that you are if you did not receive any error
message when activating the unbounce link.

There is nothing that Group Administration, on any group, can do to unbounce
members.  The whole idea behind a bounce probe is to not only detect that an
e-mail address is existent, but that someone's reading it and reacting to
content.  That is something that only the member who receives a bounce probe
can do.

For those who want additional information about how bouncing works, and from
the Group Admin perspective, see this page from the Groups.io Owner's
Manual, paying particular attention to the last line that starts with,
"Important!"
https://groups.io/helpcenter/ownersmanual/1/additional-information/groups-io-bounce-handling

*Please do not send test messages to see if you are unbounced*.  If you
receive a single message that anyone has sent, you are unbounced, and our
traffic is high enough that messages tend to come through pretty regularly.
--

Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042

[ Regarding the Supreme Court refusing to hear the case brought by Texas to
overturn the votes certified by 4 states: ] Pleased with the SCOTUS ruling,
but also immediately slightly terrified of where this crazy train goes
next.  We should know by now there’s a bottomless supply of crazy.

~ Brendan Buck, former adviser to Speakers of the House Paul Ryan and John
Boehner