Is the question mark optional?

When asking a written question?

No.

Thanks, Old Goat.

If I ask a question and nobody responds to my post after one hour, and I want to draw attention to it and hope a member replies to what I posted, should I use a question mark in the first sentence I posted on this topic?

It depends. If English isn't your first language, then people will probably still reply, but then maybe put you right at a later stage.

But I would advise that you use a question mark in every such instance, as your sentence construction may not be good enough to make it clear that you are actually asking about something.

no, the gramatically right thing to do is use question marks at the end of any question