Ken,
If someone is on a number of very busy lists, this would seem to make
bouncing more likely due to the amount of traffic going to one account.
Correct, in the sense that each message sent is an opportunity for the receiving service to reject ("bounce") one of the messages.
In the case of yesterday's Gmail problem, someone whose group subscriptions sent no messages during the affected interval would not have been put on Bouncing status.
But the message logged shows an explanation that clearly say the issue is
Groups.io is sending or connecting too many times and needs to throttle
back. It would serve as a clue that would impact many members as I guess the
threshold is for all of Groups.io mail servers talking to the
Spectrum/Charter mail servers. I hope the solution they are working on is
taking that into account.
For that circumstance, yes. Several months ago Mark implemented means to regulate how many simultaneous connections Groups.io forms to any given service, and IIRC how many messages to deliver during each connection. So it should be a matter of tuning those parameters to suit the limitations of a given service, while working with the service to increase what they allow if their limits are causing noticeable message delay.
Setting a number of members to bouncing is only a temporary and poor fix as
that reduces the continuing traffic from GIO to Spectrum/Charter.
Setting the individual accounts to bouncing is not intended as a fix - it is a response to the service's rejection of messages. If there's a large number of rejections from a given service what has to happen from there is an investigation into the underlying cause, hopefully with the cooperation of that service.
In the case of Gmail yesterday the cause appears to have been a temporary failure of their email servers to recognize valid destination addresses.
There was also yesterday a listing by SORBS (a blacklist service) of one of Groups.io's outbound servers as being a spam source []. That may have caused some email services to start rejecting messages from Groups.io rather than simply diverting them to the member's Spam folder.
Shal
Shal Farley