“unsubscribe” link from the email is taking me ti the page with admin username

I recently created a newsletter. There are two links in the footer: “unsubscribe” and “manage your subscription”. The second one is working fine, but first one has an issue.

For example the admin of my site has username: “Xyz”, and I have sent the email to the user with username “abc”. However, when “abc” clicks on the unsubscribe link, the page opens where it’s written:

[Confirm you want to unsubscribe?
xyz

simply click on this link to stop receiving emails from us.
Yes, unsubscribe me.]

This is not happening to this specific user but to everyone. All users are seeing xys instead of their respective usernames. When they click on Yes, unsubscribe me, it takes them to manage subscription page where everything is fine however. So please help me resolving this issue. I want to show the user’s username, not admin’s.