ActiveCampaign SMTP Settings and Configuration (2026)

One of four jobs is usually behind that search, and only one needs a relay: handing mail to ActiveCampaign for delivery (not possible), sending transactional mail alongside marketing mail (a separate relay account), connecting your own mailbox to the Deals CRM (your provider’s settings, not ActiveCampaign’s), or configuring SPF, DKIM and DMARC so campaigns reach the inbox. That last one is the common case, and it is fully supported.

For the relay leg the natural companion is Postmark, owned by ActiveCampaign since 2022 but billed separately. Teams already on Amazon SES, SendGrid, Brevo or SMTP2GO lose nothing by keeping them.

Quick reference

Why ActiveCampaign has no SMTP relay

ActiveCampaign is a marketing-automation and CRM platform, not email infrastructure. Its sending stack is deliberately closed: messages are composed in-app or pushed over the v3 API, and leave from ActiveCampaign’s own marketing IP pool. Opening a relay would mean accepting arbitrary traffic onto those IPs from servers it cannot inspect — the fastest known way to wreck a shared reputation pool. Relay vendors price and staff for that risk; automation vendors do not.

The consequence shows in the group’s own product line. ActiveCampaign acquired Postmark in 2022 and kept it standalone on separate infrastructure; the official app listing sells that separation as the benefit — “different sending IPs” for marketing and transactional. Klaviyo and Mailchimp reason the same way. If you need both from one login, Brevo fits better.

What you actually need instead

Sending transactional email

Receipts, password resets and shipping notices need a relay with its own reputation, and the documented path is Postmark. You sign up at postmarkapp.com, get approved and pay Postmark directly — no ActiveCampaign plan includes Postmark volume. Its SMTP endpoint:

Host      smtp.postmarkapp.com
Ports     587 (STARTTLS, recommended) | 2525 | 25
Username  your Postmark Server API Token
Password  the same Server API Token
Header    X-PM-MESSAGE-STREAM: outbound

Broadcast streams use smtp-broadcasts.postmarkapp.com, and a dedicated SMTP Token can replace the server token (Access Key as username, Secret Key as password). Free tier is 100 emails per month; paid starts at $15/mo for 10,000. See the Postmark SMTP guide. What ActiveCampaign adds is orchestration: its Send a transactional email action authorises against your own Postmark account. That is a connector, not a provisioning step.

Connecting a CMS or app

A WordPress site, a Laravel app or a Django backend that wants an SMTP endpoint cannot point at ActiveCampaign. Point it at a relay — Postmark, Amazon SES, MailerSend and SMTP2GO all expose standard hosts on ports 587 and 465. Keep ActiveCampaign for what it does well: the official WordPress plugin adds site tracking and forms, and the Gravity Forms and WPForms connectors push submissions into automations over the API.

Routing notifications

Alerts that originate in ActiveCampaign need no relay: automations email a fixed internal address directly, and webhooks at /api/3/webhooks push events into Slack or PagerDuty with no email leg at all. Alerts originating in your own infrastructure should ride whatever relay already carries your system mail. For behaviour-triggered product messages rather than plain alerts, Customer.io spans both.

Sending domain authentication

This is the setup that determines whether ActiveCampaign mail reaches the inbox, and where most “SMTP settings” searches should end. It lives in Settings › Domains on all four plan types. Propagation typically takes 5 to 10 minutes.

SPF and DKIM setup

ActiveCampaign handles SPF differently from almost every other ESP, and it trips people up constantly. There is no include: value to paste. The docs say plainly that “you don’t need to create an SPF record or modify an existing one”. You point a Mailserver Domain CNAME at ActiveCampaign and it serves the SPF record at that delegated hostname.

DKIM follows the same pattern: instead of a TXT public key you publish a per-account CNAME pair in the acdkim1._domainkey / acdkim2._domainkey form. The shape is documented; the targets are generated per account and shown only inside your own dashboard.

; ActiveCampaign sending domain — copy exact targets from Settings › Domains
; 1. Mailserver Domain: SPF delegation by CNAME, NOT an SPF include
mail.yourdomain.com.                 IN  CNAME  <target shown in your account>

; 2. DKIM: per-account CNAME pair, no TXT key to paste
acdkim1._domainkey.yourdomain.com.   IN  CNAME  <target shown in your account>
acdkim2._domainkey.yourdomain.com.   IN  CNAME  <target shown in your account>

; 3. DMARC: ActiveCampaign writes a placeholder policy during setup
_dmarc.yourdomain.com.               IN  TXT    "v=DMARC1; p=none;"

Two paths exist. Configure Domain is preferred: ActiveCampaign detects your DNS provider and writes the records itself through native integrations with GoDaddy, Cloudflare and Amazon Route 53. Set up manually confirms ownership by email, then hands you a table to copy into your DNS host. Use the automatic path where supported — it removes the most common failure, a mistyped CNAME target.

DMARC alignment

ActiveCampaign adds a DMARC record during setup and is candid about what it is: “a basic DMARC record as a bare minimum”, explicitly “a placeholder” with “no impact on the messages you send but it will satisfy Gmail and Yahoo’s requirement”. Treat it as a compliance floor, not a policy: p=none quarantines nothing and rejects nothing.

Replace it with your own record carrying an rua= reporting address. Run p=none with reporting for 2 to 4 weeks, confirm every legitimate source aligns — campaigns, relay, helpdesk, invoicing — then move to p=quarantine and eventually p=reject. Since ActiveCampaign delegates SPF to a hostname it controls and signs DKIM with delegated keys, alignment works once records resolve; the usual breakage is authenticating yourdomain.com while sending from news.yourdomain.com.

Sending limits

ActiveCampaign meters sends monthly against your contact limit rather than throttling per hour, so the per-hour and per-connection figures other relays publish do not exist here. Limits below reflect plans purchased on or after June 3, 2024.

The deliverability guide adds voluntary warm-up guidance for lists above 50,000 contacts: 25,000 per day in week one, then 50,000, 75,000 and 100,000. That is reputation advice, not an enforced ceiling — nothing blocks a larger send, your complaint rate just pays for it.

Common mistakes

Pairing ActiveCampaign with an SMTP provider

Recommended setup

Run two systems on one authenticated domain. ActiveCampaign owns marketing and lifecycle mail, driven in-app or through /api/3/contact/sync and tag-based triggers. A relay owns everything your application generates. Postmark is the path of least resistance: it is the only relay ActiveCampaign builds a native automation action for, so a transactional send fires from inside a workflow rather than your backend.

At higher volume cost per thousand dominates — Amazon SES if you are already in AWS, MailerSend or Resend for a developer-facing API with less setup, Mailgun where inbound routing and log retention matter. None integrate into AC automations, so trigger them from your backend or a webhook at /api/3/webhooks.

Keeping the two systems from conflicting

The first failure mode is double-sending. Both systems hold the same contact, and it is easy to build an automation that emails a receipt your application already sent. Draw the line by message class: anything carrying an order ID, token or password belongs to the relay; anything with an unsubscribe link belongs to ActiveCampaign. Then enforce it — tag transactional-only contacts and exclude that tag from campaign segments.

The second is DMARC. Two senders on one domain means two authentication paths that must both align, and adding a relay after ActiveCampaign is already authenticated is where policies break. Publish the relay’s DKIM selector alongside the acdkim1 / acdkim2 CNAMEs — selectors are namespaced and coexist fine. SPF is the sharper edge: ActiveCampaign needs no include, your relay almost certainly does, and an SPF record is hard-capped at 10 DNS lookups. The clean answer is subdomain separation — campaigns from news.yourdomain.com, transactional from mail.yourdomain.com, each with its own records and reputation.

Frequently asked questions