Group email id - bouncing

Hi experts,
I have one mail server with version 6.9 installed and the other 7.1 installed. In 6.9 version, i have users and groups separately, when I create a group and add members to it, the mail which i sent to this group id, they are delivering to all the members in the group.

Where as, the same i followed in 7.1 it is bouncing.
What I am missing?

See:

So, it is not possible in version 7.1?

No. And why on earth would you be on 7.1?

then, in that case, can I roll back to 6.9?

@danb35 observed the same in version 7.6.1810 (final) also.
Any work around ?

What work around there is, is in the thread I linked above–IIRC, it’s released in the testing repo.