I need help with subject line of query

I've had an agent decline a query, but invite me to send along anything else I have.

My question is, how would I send that new query?

Should I send it in the same thread as the rejected query? I think that's odd.

Should I send it as a new thread/query, but how do I bring it to the attention of the agent that it's "kind of" been requested?

I know to reference it in the query letter itself, but I'm talking about the subject line.

What would anyone suggest as a subject line? Just send it as a typical query, or use some kind of key word?

Yes it was a personalized post script added after the form rejection inviting me to send along something else.

This happens when an agent likes your writing, recognizes you have talent or however you want to put it, but the particular ms you sent just isn't right at that time.

So, I'm wondering how to address the new query. It seems to me a step up from the slush pile, but I know it isn't a request for a full submission either.

I supposed it would be like how a person is asked by an agent at a conference to send along a query, how does one address that?

Yes, thanks, that's what I was thinking, but I was wondering about it because, you know, we always have to have something to worry about to get in the way of just doing it.

What I assumed was I would send it as a new query and reference the request in the first sentence as an opening, such as how you'd say I see in your blurb on #MSWL you're interested in fishing and boy, do I have a whopper of a fish story for you...Or you'd say I caught your lecture at CrimeBake, and this is right up your alley. But really you'd say, you asked to see something else, here it is, etc.

But because of all the #ing that goes on now, I see some agents say they want you to # the subject line, to greenlight you through the slushpile, so I was wondering if this would be similar.

I've also seen agents say to keep all email correspondence to the original thread, so

Yes. That makes sense. Thanks.