Under the federal CAN-SPAM Act (and several other international variations), an Unsubscribe link is mandatory in all bulk emails for both for-profit and nonprofit organizations. While this hasn't been strictly enforced in the past, it has some serious and immediate consequences for deliverability if it is not present:
Spam filters look for an unsubscribe link as an indicator of legitimacy. Emails that don't have an unsubscribe link are by definition breaking the law, and are therefore very likely to be filtered as spam and never delivered to the intended recipients.
Sender reputation monitoring services are increasingly being used by ISPs/ESPs to make judgments about whether to deliver email by specific senders. One thing that weighs heavily in sender reputation is CAN-SPAM compliance.
Research shows that emails that do not feature an unsubscribe link have a much greater probability of being reported as spam to an ISP/ESP, reports that weigh heavily against sender reputation. If someone doesn't want an email, you are far better off if they unsubscribe rather than reporting your email as spam.
As part of earning preferred sender status with several sender reputation monitoring services, we had to demonstrate that the Unsubscribe link was mandatory. Therefore, an Unsubscribe link will appear at the bottom of every email from eNotify or Messages.
If you’d like to choose how to format your Unsubscribe link, you can use the special link in the content block.
eNotify and Messages will check for one of these links when an email is sent, and if it hasn't been included, it will append one.