If your account is switched to the opt-in subscription method, you will see an option to set your emails as transactional.
Transactional emails are emails that contain no marketing content. They are emails you must send regardless of the recipients' unsubscribes or preferences. Examples would include sign up confirmations, form submission confirmations, order confirmation/receipt, or emails you legally must send.
Transactional emails sent via ClickDimensions will not check against any unsubscribe records, subscription preferences, or the Do Not Allow Bulk Emails and Do Not Allow Emails fields. The only thing that will be checked is the blocked list which contains email addresses that have had too many bounces or have marked your emails as spam.
These emails will not check to see if there is an unsubscribe or subscription management link in the email.
Send transactional emails with caution. Make sure you are abiding by any laws you are subject to abide by. Transactional emails are only meant for non-marketing, necessary emails.