Outbound Glossary
Unsubscribe link
An easy way out. Leaving it off does not reduce complaints, it converts them into spam reports, which cost far more.
An unsubscribe mechanism lets someone stop hearing from you in one click. Large providers now expect a header version for bulk senders, and the visible link remains normal practice.
Some senders leave it out of cold mail to look more personal. That trade goes badly: a person who wants out and cannot find the door presses the spam button instead, and that single action does more harm to your sending than losing the contact ever would. At the volumes most cold campaigns run, a plain line offering to stop is enough. Once you are sending at the volumes the large providers treat as bulk, they expect the one-click header version as well, and that is a requirement rather than a matter of taste.