lamer... how to send group email efficiently

[Harry Putnam]

Its a lamer question for 10+ yr gnus user but I've never had occasion
to send group emails.  Just not something I do.

Now I have need of a nice efficient way to send emails to a couple
dozen recipients... and looks as if I will be doing this every couple
of weeks.

The list of recipients will change over time but only by a few
deletions or additions... so it would be nice to be able to just add
or subtract email address' to/from something and gnus/emacs will do
the rest.

There must be a number of folks here who have developed nifty ways to
do this... please anyone share your technique.