Do you send out mass emails with a service, something like MailChimp or Constant Contact?
You may be losing subscribers that you don't want to lose. Today I unsubscribed from a couple of email lists and I liked getting the emails, but I have multiple emails and my priority email is where these mass market emails were going and they're using a service.
Perhaps it's MailChimp, perhaps it's Constant Contact, great services, by the way, or maybe it's one of the thousands of others out there. But I didn't want to unsubscribe. What I wanted to do was change where the email arrived. So I looked for and update preferences or change your profile kind of link. The only link they had was an unsubscribe link and so all I could do was hit that link and the only option on that link was to unsubscribe.
There was no option to change the email where it arrives or to change my profile, which would have been useful. Instead, I got off their list.
Now, if you're sending out mass emails and you don't have an option for your people to change the email at which they receive your mass emails, they may still want them. But if you don't give them a choice to change their email, you're going to lose them. And I say this assuming that many people have many emails like I do.
So, you might want to look at that and find out how to give the folks you're sending emails to an option to change their profile, change their email instead of just the option to unsubscribe.