The basic rule is that as long as your post has some content related to the primary subject of the list, and does not contain much off-topic material, then it is fine for the list.

Please note - Orchid is a flame free group! You should not post inflammatory (aka flame) mail to the list. It is perfectly fine to disagree with people publicly, but be careful how you do it. For example, if you think someone is giving wrong information on a particular subject, it may be fine to say “this idea is wrong,'' but it is over the line to say "you are clueless”

On the flip side, if someone posts something with which you are in particular agreement, that's great. You should not, however, follow up to the list with a post containing no more than "Me too!'' or "Amen!'' If you have something of substance to add to the discussion, then by all means do so, but if you simply wish to express a simple agreement, then do it in private mail.

You should also not repost private email to the list unless you have obtained prior consent from the author. Such reposting in some legal jurisdictions may be a violation of copyright, or other rights of the original author.

See also - How can I share files and pictures with the list?