I think that's awful (no offense). I get tonnes of link requests, and other such emails every day. I don't have the time to reply to them and neither should I have to. Some of the emails state that "As they haven't had a reply from me... etc..." And then presume to suggest that I should take time out of my busy day to reply to their unsolicited emails.
Continuing to ask after no reply the first, or even second, or as you say 5th time is not getting the message and is little less than harassment.
A lot of people, like myself don't reply because:
a) It open the doorway to more such spam, and
b) Sometimes replies are little more to the sender than confirmation the email exists and responds so they can sell your data
I think it's rude to keep sending people emails. Why should I have to write "No" hundreds of times per week when I didn't even ask for the email in the first place.
So, what you're saying is that you're one of those people who hassle and bug people like me who are just trying to get on with my work, and you won't ever stop despite the fact that I don't reply?
It gives all of the industry a bad name when people do stuff like that.
Also, why should I have to unsubscribe, when I never subscribed in the first place? Not to mention that most of these requests don't have the option to unsubscribe anyway.
Sorry for the rant, nothing personal but I see it as pressure sales via spam... which I'm surprised works at all to be honest.