Contacts
The people you can email — subscription state, custom fields, and imports.
Contacts are individual recipients: an email address plus optional name and custom fields you define. Each contact has a marketing subscription state — subscribed contacts are mailable; unsubscribed or suppressed contacts are skipped automatically and never receive campaign mail.
Importing
Import contacts in bulk from CSV. The import is per-row resilient: valid rows are created even if others fail, and you get back a summary of how many were imported, skipped (already present), and rejected — with the row number and reason for each rejection — so one bad line never sinks the whole file.
Custom-field limits
Custom fields are capped per contact (and on key/value length) to keep records lean. Rows that exceed the caps are reported in the import's invalid list rather than truncated silently.
Deleting a contact
Deleting a contact removes them from every segment they belong to. If any of those segments are targeted by an active (non-terminal) campaign, the confirmation tells you how many segments and campaigns are affected so the impact is explicit. There's no hard block — people legitimately churn — but you delete with eyes open.
Contacts are the first link in the core flow: group them into Segments, then send to a segment from a Campaign.