(BTW I've manually re-subscribed on 9 March the 6 @gnu.org addresses that were automatically unsubscribed in the morning).
Thank you.
Concering the reasons of the bounces, I can't give you further details, but I hope our sysadmin will be able to look at this shortly.
I guess the gnu.org mailserver had some trouble in late February early March (@gnu.org users: can you confirm?), because the bounce configuration parameters for this list are set to default values; anyway I'll have a closer look at them, please report any other problems you might find to system-hackers@fsfeurope.org
There weren't any problems with the mail on @gnu.org around late February, early March. The @gnu.org mail servers handle quite alot of mail, and only discussion@fsfeurope.org was misbehaving for me.