The mail problems with lwip-devel aren't related to the upgrade. I found that the spam detector that the FSF runs on lists.gnu.org was wrongly considering many posts to the lwip task and bug trackers as spam, and filtering them away. I've submitted a request to FSF sysadmin to fix it, one way or another. We can't change the lists.gnu.org configuration ourselves.
I can resend the filtered messages I have at hand -- there are about 50 of them. Do you want me to? Sorry for the trouble, Karl
