We use NXT emails and have found that when a constituent unsubscribes, sometimes accidentally or in haste, the only way to re-subscribe them is to contact support with an email containing specific information from the constituent in order to be allowed to opt-back in.
This is a tedious process and not exactly the most time-sensitive either. It would nice to have a standard re-subscribe email template to use as a workflow email to allow constituents to opt back into emails from our organization via another email (and it could work logically like event confirmations still do even if they've unsubscribed) without having to go through us and then support.
Also, when people DO re-subscribe, it doesn't update the solicit code on the constituent record. When they unsubscribe, and email opt in becomes opt out, but it doesn't do the reverse when someone re-subscribes.
We have spent HOURS on this process over the past few months. Recently, we've seen a new NXT feature under Marketing>email options to enter an email address for reinstatement (opt-in) which simplifies getting a support person involved, but it is designed to send a spam target email with a personalized single-use link for that email address which requires each address to be entered in that form individually.
Under a separate idea I have requested that feature to be expanded to allow a generic link to be available for constituents to go to directly.
It is also a hassel because not each support member knows the process. This past summer I just had to provide the emails. Now I'm working with an agent who needs an email. If this is supposed to be an email system to eliminate us needing Constant Contact or MailChimp, then we should have full capabilities without relying on support.