Who can be emailed: subscriptions and unsubscribes

The rules that decide whether a person gets your emails, and how unsubscribing works.

UserSignal only emails a person when all of these are true:

They are subscribed.
Their address was confirmed by you: it came through the API, an import, or the widget with identity verification.
They are not on the list of people you never email (unsubscribed, marked an email as spam, or bounced).

Campaign audience counts already apply these rules, so the number you see is the number that will be sent.

Why the address must be confirmed

Anyone can type an email address into a browser. To keep strangers from being emailed in your name, an address only becomes emailable when your own server vouches for it. See Identifying Users for identity verification, or send contacts through the API.

Subscribed or not

Contacts are subscribed unless told otherwise. Your app can set this for each contact (the subscribed field in the API, or a column in an import), for example from a "send me news" checkbox in your own settings.

Unsubscribing

Every email has a one-click unsubscribe link in its footer. Mail apps such as Gmail also show their own unsubscribe button, which works the same way.
Unsubscribing takes effect at once, for campaigns and automations.
It belongs to the address: if the same person exists as several contacts, all of them are unsubscribed.

When someone marks an email as spam

They are unsubscribed at once and added to the list of people you never email. This can't be undone, by you or by them.
It counts towards your spam-complaint rate, which pauses sending above 0.1%.
Yahoo, Outlook and most other providers report each complaint. Gmail does not say who complained, so those people stay subscribed unless they also unsubscribe; Gmail's totals are in Google Postmaster Tools.

What you can and can't undo

An unsubscribe or a spam complaint is the recipient's decision. Only they can reverse it, by resubscribing from the same link. You can't resubscribe them from the dashboard or the API.

Seeing who unsubscribed

Email › Sending health lists everyone you never email, with the reason and the date. Your app can also read new unsubscribes, complaints and bounces through the API to keep its own records in step.