Every email you send from Kit already includes Gmail's one-click unsubscribe. Kit adds the required headers to every send, so there's nothing for you to set up.

In Gmail, subscribers see an "Unsubscribe" link at the top of your email, next to your sending address.

It can also appear when they hover over your email in their inbox list.

Gmail decides when to show the unsubscribe link and when to hide it. That choice sits with Gmail, not with you or with Kit, and a missing link doesn't mean the header is missing from your email.

One thing to know if you're testing: Gmail won't offer to unsubscribe you from your own email, so sending a test to yourself won't show the link.

To confirm the headers are in place, open one of your emails in Gmail, click the three-dot menu, and choose Show original. Look for List-Unsubscribe and List-Unsubscribe-Post.

Some Gmail users also have a Manage subscriptions view. It lists every sender they're subscribed to, shows how many emails each one has sent recently, and puts a one-click unsubscribe next to each sender.

If you see a short spike in unsubscribes with no change on your end, this is often where it came from.

Making it simpler to opt out can lift your unsubscribe rate. The subscribers who leave this way were usually already disengaged, so what you're left with is a list that reflects who actually wants to hear from you.

When opting out is hard to find, people report the email as spam instead. Spam complaints hurt your domain reputation and your inbox placement for everyone on your list, while an unsubscribe is a neutral signal. Keeping complaints below 0.3% is part of Gmail and Yahoo's sender requirements.