[Gambas-user] Answer mail so that it's in the same thread

[John Rose]

An elementary question about this mailing list:
Benoit told me "please *answer* mails that are in the same thread. Do
not create a new mail each time, because then it is very difficult to
follow the talk.". I don't understand this. I don't receive an email
message each time someone posts to the Gambas Mailing Lists: I have set
my preference to receive the digest. How do I "answer" an email so that
it shows in the same thread. Do I set the subject to be "Re: original
subject" or do I set it to "original subject" or is there some other
way?