I saw this question, which asks about a Python templating library that has only 4 mentions on SO. I get the feeling the question has a high chance of going unanswered, so I posted a comment suggesting the OP ask on the project's mailing list. After that though, I began to wonder whether it was the right thing.
Was my comment appropriate? Is there a better way to handle such questions?
I think that your comment is helpful because you also state in the comment the reason why you think it might be better to ask on a mailing list. The asker can make his/her own judgment whether he/she trusts your comment or not based on the reason you wrote.
In contrast, just writing “Ask on a mailing list” will not be so helpful (even if it is ultimately the right thing to do) because the asker will not have any clue whether he/she should trust the comment or not.