Groups.io is the new place where Hams and I guess many others are moving their discussion groups from Yahoo. I was first notified over a month ago that QRPLABS was moving over, I created an account with groups.io and sure enough if by magic it apppeared in my new groups.io account. Using it has become very easy and straight forward, and I find it doesn't suffer from the access lag that Yahoo groups suffered. Since joining, the BITX20 group has also moved and so have a few others, I expect many others will follow.
Groups.io has a full automated transfer service for groups users that wish to transfer over:https://groups.io/static/transfer I have not used the transfer myself, but all the groups that have moved I am member of that have chosen to move to the new service appear to have gone over smooth, and they popped into my group.io account.