A way towards good inboxing requires you to follow best practice:
In order to add an unsubscribe link to your email, you'll need to use the {unsubscribe_text} token. This placeholder will populate your email with the right - and contact specific - unsubscribe link.
If you would like to add the webview link, you can use the {webview_text} token.
The text of these tokens can be edited in your configuration area:
Scroll down, and you'll find the text, that is added to your emails upon using these tokens.
You have the option to customize your own html text and just add the unsubscribe/webview URL, not the whole html text. You can use the {unsubscribe_url} and {webview_url} respectively.
Example:
You can any time unsubscribe <a href="{unsubscribe_url}">here</a>
Or
If you can'T see the images, click <a href="{webview_url}">here</a>
There are a bunch of other tokens you can use to customize your emails. Here is the full list: