Thank You Mr. Editor for hearing all these good suggestions, and helping everyone out by implementing them!
Here is something I think would be useful. If a moderator rejects a comment for whatever reason, send the poster an email with the original message so he could edit it so it is appropriate and he can repost it without the objectionable parts. If someone writes a whole megila of a comment and it never gets posted, the original poster doesn’t have a copy of his original message and may not want to type it all over (without the objectionable parts.) Also, maybe the moderator can include a note in the email why it was rejected.
If the moderator edits out the objectionable parts (instead of rejecting it outright) , which is actually a better idea if possible, then just out a little note where it was edited with something like “edited by moderator”. I don’t think it is necessary to make the poster feel bad by writing WHY it was edited for everyone else to see, the poster will get the hint anyways.