1. Design the content in Brevo -- Atlas deliberately doesn't build email designs itself; Brevo's own drag-and-drop editor gives far more creative control. Log into app.brevo.com directly and either build a full campaign under Campaigns (save it as a draft -- don't send it from there) or a reusable design under Templates. Either one becomes pickable back here once saved.
2. Trigger a campaign -- in "Send a Campaign" below, choose a lane:
   • Full Campaign -- pick a synced list under Recipients (this is who the campaign goes to). Picking one that hasn't synced yet shows its own Sync Now right there. Don't have a list yet? Expand Manage Lists right below Recipients -- it opens on its own when there's nothing to pick. Name a new one, optionally narrow it to one Track, optionally check one or more Source of Import values to narrow further (leave everything unchecked for "any"), then Create List Definition and Sync Now to push it to a real Brevo List (creates an "Atlas" folder the very first time). A list can't be targeted until that sync completes at least once. Delete on a list under Manage Lists removes it from Atlas only, with a confirm prompt first -- the real Brevo list stays untouched either way. Once you've picked a list under Recipients, a separate Delete this list… shows up right there too -- same Atlas-only default, but with a checkbox to also permanently delete the real list in Brevo in that same step (contacts themselves are never deleted, only the list/grouping) -- for the occasional test or very outdated list you actually want gone from both places at once. Sync Now has always been additive only -- narrowing a filter and re-syncing never removed anyone who stopped matching. Now it checks for that first: if it finds contacts in the real Brevo list that no longer match, it stops and asks -- Remove & Sync, Sync Without Removing, or Cancel -- rather than silently doing either.
     For the campaign itself: either targets a campaign you've already built as a draft in Brevo's editor, or creates a fresh one from a template (your choice, via the toggle). Either way you can optionally set a future send time, or leave blank to send immediately -- a template-based send with no schedule set is a fast, one-click, list-wide blast.
   • Single Contact -- no list involved at all. Search for a target by name (if they're in Atlas, pick which of their emails to use) or just type any email address directly, pick a template, and it sends that one templated email straight to that one address via Brevo's transactional send -- not an Email Campaign object in Brevo, so it won't show in Brevo's own Campaign reporting, only here under Campaign History. Opens/clicks don't flow back for these either, unlike list-based sends -- Campaign History records that it was sent, not whether it was opened. This recipient was never added as a real Brevo Contact, so a template's usual {{contact.FIRSTNAME}} tag has nothing to resolve -- Atlas sends the picked name through as {{params.FIRSTNAME}} instead for a "Hi Name," salutation. Add that exact tag to the template's own salutation line in Brevo's editor for it to actually show up -- a manual placeholder like [First Name] sitting there instead won't resolve to anything; it has to be replaced with the literal {{params.FIRSTNAME}} tag text. The Design Preview on Review will show exactly what's really going to send either way.
   • Curate Campaign -- identical to Full Campaign in every other way (same Sender/Design/Subject/Schedule/Review/Confirm), except Recipients only ever lists Curated Campaigns -- hand-picked, frozen lists, never the filter-based ones Full Campaign uses. This tab is the "idiot-proof" entry point: it can't be confused with a filter-based send, since a Curated Campaign never shows up mixed into that other dropdown. Don't have one yet? This tab tells you exactly where to build one -- see the next bullet.
   The panel mirrors Brevo's own Sender/Recipients/Subject (+ Preview text)/Design layout -- on an existing draft, every field except Recipients is an optional override (leave blank to keep whatever the draft already has); on a template-based send, Sender/Subject are required since there's no existing value to fall back to. Show additional settings adds Reply-To, Tag, UTM Campaign, a "View in browser" link, and Send at Best Time (Single Contact only gets Reply-To and Tag -- the rest are campaign-only concepts Brevo's transactional send doesn't have).
3. Review, then confirm -- clicking Review always shows exactly who, what, and when before anything actually sends. Nothing fires on the first click.
4. Track it -- every campaign triggered from here shows up in "Campaign History" below, tagged by track/brand automatically, searchable by name and filterable by track/type. Each row shows its own opens/clicks/bounces/unsubscribes as they come in from Brevo -- raw counts, not a percentage, since Atlas has no reliable total-recipients figure to divide by. Single Contact rows show "Not tracked" instead of zeros -- a transactional send's engagement genuinely never flows back, that's not an empty result. Every target that send actually reached also gets a note logged on its own TDP, under Notes / History -- campaign name, subject line, and timestamp. Check boxes to select several rows and Delete Selected, or use a single row's own Delete -- either only removes that record from Atlas -- it never un-sends the email and never touches those TDP notes.
5. Add one contact to a list? -- not the same thing as Single Contact above (that sends directly, no list). "Add an Individual Target" below instead pushes one contact straight into an already-synced list, even if they don't match that list's filter -- for a VIP you want included in a future list-based campaign regardless of criteria.
6. Building a Curated Campaign -- for a hand-picked list, not a filter. On any Target List page, use the full search there (region, category, agency/client type, specialties, brand, tier, etc.) to find exactly who you want, check their boxes, then use the toolbar that appears: Add to Curated Campaign either adds them to an existing one or names a new one; Remove from Curated Campaign (not just for targets that already show the badge -- works on any selection) pulls the selected ones out of a Curated Campaign you pick. A note right there spells out what both really do: a Curated Campaign is a real Brevo List, so adding or removing changes who actually gets emailed once it's synced and sent, not just an Atlas-only grouping. Unlike a regular List Definition (a live filter that recomputes every sync), a Curated Campaign is a frozen snapshot -- exactly who you picked, locked in, never silently gaining or losing members later. It becomes a normal, syncable list under Recipients in the Curate Campaign tab above. A target that's part of one shows a "Curated" badge in its own Brevo column on the Target List (filterable/sortable there too, and with its own one-click remove right on the badge) so it's easy to tell a hand-picked send apart from a broad-audience one at a glance. "Add an Individual Target" below works on a Curated Campaign too, and keeps this same record in sync when it does.
7. Suppression Management -- an address that hard-bounced, unsubscribed, or was marked spam is automatically excluded from every future sync/send; this section (base of page) lists all of them, filterable by Hard Bounce / Unsubscribed / Spam / Manually Suppressed / Soft Bounce. Clear suppression is Atlas-only and reversible -- for a false positive (address got fixed, complaint was stale). Remove from Brevo is real: it permanently deletes that contact from Brevo entirely, with a separate confirm, since it can't be undone from Atlas -- it does NOT touch anything in Atlas itself (the target, its history, and this suppression record all stay exactly as they were; the two are deliberately separate decisions). Soft bounces (temporary failures) never auto-suppress on their own -- the Soft Bounce Screening list lets you review repeated ones and manually suppress a genuinely bad address before it costs you anything.

This is the first time this write path has run against your real Brevo account. For your first real test, scope the List Definition as narrow as you can (a specific Source of Import rather than a whole Track) so a surprise lands on a handful of contacts, not your full list.