Beat me to it. Why isn’t every unsolicited pitch without an unsubscribe link immediately blocked/marked as spam?

Is the presence of an unsubscribe link a useful signal? I presume that just marks your email address as active in the spammer's database.

I think so too and have a funny conunndrum: I frequently get emails from some "Relations management" companies that they are including my contacts in a catalogue to sell to clients. I can opt out by clicking a link.

So either I click and it may delete me, or it will confirm my address is real. I err on the side of not clicking, but I'm sure many less technically minded colleagues make the click.

Not to mention the obviously unrelated-to-publishing, dodgy sounding email addresses. Red flag #1 where only a single red flag is needed to discard it.

Having said that, less technically minded people, as authors may be, may not even notice that.

Many people don’t even know that Outlook can still show the source email address because it shows you the name instead.

I mark as spam also ones with unsubscribe link.

According to claimed timeline he decided to do it later. At that stage responding to spammers makes sense.