I see this quite a lot:
- I give my business card to a person.
- They subscribe me to their newsletter.
A better solution to this:
- Never subscribe anyone to the newsletter without having the permission to do so.
- Always send an email after a conference to anyone who gives you their business card at least with their contact data.
- If you have something worthwhile to add in your email, add it. Things include:
- Photo(s) from the event – made by you.
- Some links to some follow-ups of the event (it’s nice if someone sends you these links).
- A specific thing you remember from the conversation with that person, and on which you can contribute.
I consider these a solid improvement to subscribing people to the newsletter.