With all the recent Yahoo data breach furore and various problems at times of access to Yahoo groups, many Amateur Radio groups are turning their backs on Yahoo and moving to a new group service.
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 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.