Unitpost
Contacts

Your audience, in one place.

Custom fields, segments, consent. Pay for sends, not contacts.

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Every contact

Everything about a contact, on one screen.

Identity, fields, topics, activity. One screen.

  • CSV import

    Map columns. Existing contacts are skipped.

  • Activity trail

    Every change, logged per contact.

  • Deliverability

    Mailable or suppressed, with the reason.

ada@example.comMailable

Ada Lovelace

ada@example.com

Subscribed

Fields

companyAcme Corp
planpro
seats12
signup_date2026-01-14

Topics

Product updatesNewsletterPromotions · off

Activity

  1. Subscribed to Product updates2d
  2. Added to segment “Beta”5d
  3. Imported from CSV3w

Custom fields

Store any attribute, your way.

Text, number, boolean, date. Reference as {{ key }}.

  • Four types

    Set a default when a contact has no value.

  • Safe to rename

    Keys migrate. Deletes strip cleanly.

Custom fieldsUse as {{ key }}
LabelKeyDefault

Company

company

—

Plan

plan

free

Seats

seats

1

Signup date

signup_date

—

Beta access

beta_access

false

Segmentation

Static lists and dynamic segments.

A hand-picked list, or a filter that stays live.

  • Dynamic

    Membership recalculates. No re-tagging.

  • Operators

    is, contains, greater than, is-set — per type.

  • Everyone subscribed

    Built in. Always current.

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Active Pro usersDynamic
MatchAllAnyof the following
planispro
signup_dateis greater than or equal to2026-01-01
last_nameis set
Resolved live on every send312 contacts

Personalization

Personalize with every field.

{{first_name}}, {{email}}, or any custom field. Per recipient at send.

  • Any field

    Subject or body. Built-in and custom.

  • Caught before send

    Missing values return 422. Never a raw token.

VariablesResolved at send
{{first_name}}{{email}}{{amount}}
Hi Ada, your receipt for $24.00 is ready.

Fallbacks keep sends clean when a value is missing.

Suppressions

A reputation backstop, on by default.

Hard bounce or complaint? That address is skipped. Forever, until you say otherwise.

  • Automatic

    Bounces and complaints suppress for you.

  • Reasons

    Bounce, complaint, unsubscribe, manual, API.

SuppressionsAuto-skipped on send
bounced@example.com
Bounce1h
spam@example.com
Complaint3h
left@example.com
Unsubscribe1d
old@example.com
Manual2d
Hard bounces & complaints suppress automatically to protect your reputation.

Developer-first

Manage your audience with code.

Create, update, unsubscribe, remove. One REST API.

  • Kept in sync

    Email is the unique key.

Create a contact
curl -X POST 'https://www.unitpost.com/contacts' \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{
    "email": "customer@example.com",
    "first_name": "Ada",
    "last_name": "Lovelace"
  }'
API reference

Reach the right people

A segment for every send

A list you curate, or a cohort that updates itself.

Newsletter list

A static list. Add or remove by hand, signup, or CSV.

Active paid users

plan is “pro”. Membership updates as they upgrade or churn.

Recent signups

signup_date on or after a date. Always the latest cohort.

Region targeting

Match a country or city field. Send the right copy.

Everyone subscribed

Built-in segment of everyone still opted in to marketing.

Topic subscribers

“Product updates” or “Promotions”. Send only to who wants it.

Beta cohort

A boolean field. A segment. Early access behind consent.

Win-back

Dormant accounts. Opt-outs and suppressions keep it clean.

Questions

Common questions

How do I add or update a contact from my app?

POST /api/v1/contacts with an email plus optional first_name, last_name, unsubscribed, and a custom_fields map; PATCH /api/v1/contacts/{id} updates one. Email is the unique key per workspace, and the path accepts either the con_ id or the email address, so you can sync from your own database without storing our ids. Writes need the contacts:write scope, reads contacts:read.

What's the difference between a static and a dynamic segment?

A static segment is a list you curate — you add and remove contacts explicitly. A dynamic segment is a saved filter that is re-evaluated live every time it's read or sent to, so membership follows your data with no re-tagging. Because dynamic membership is computed, the add-member and remove-member endpoints return 409 for one; you change who's in it by editing the filter.

Is there a limit on how many contacts I can store?

Every paid plan has no contact cap and you're billed on emails sent, not list size — so an unengaged list costs you nothing to keep. The free plan stores up to 10,000 contacts. A segment filter is capped at 25 conditions in total, which is a query-complexity limit rather than a limit on your audience.

Can I store custom attributes on a contact?

Yes. Register a field once with POST /api/v1/contact-fields as text, number, boolean, or date with an optional workspace default, then set per-contact values in the contact's custom_fields map. Values must be scalars so they're safe to interpolate as {{ key }} in a subject or body and to use as segment-filter inputs. Renaming a field key migrates the value on every contact.

Does Unitpost handle unsubscribes and bounces for me?

Yes, at three levels. Every contact has a global marketing opt-out, per-topic preferences they manage on a hosted page, and per-list opt-out in the data model. Hard bounces and spam complaints suppress an address automatically, with the reason recorded. Suppressed addresses are skipped on every future send — even addresses that were never contacts, which you can add yourself over the API.

Are segment filters case-sensitive?

Yes — eq, contains, starts_with, and ends_with all compare exactly, so "Premium" does not match "premium". This is deliberate: custom fields live in a JSON column whose string filters can't express case-insensitive matching, and making built-in columns behave differently would mean the builder preview, the dashboard count, and the actual send could disagree. Normalize values on write if you need loose matching.

Bring your list and start sending

Contacts, fields, segments, opt-outs. 5,000 emails a month free. No credit card.

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