Omnisend SMTP Settings and Configuration (2026)

Below: what you get instead, the DNS work that makes campaigns authenticate, the real limits, and how to pair Omnisend with a real SMTP provider. If you need a relay host and port today, go to Brevo, Postmark, MailerSend, Amazon SES, SendGrid or Mailgun-the six named in Omnisend’s own WordPress guide. Peers Klaviyo and ActiveCampaign do the same; Mailchimp is the exception, selling a relay as an add-on.

Quick reference

Why Omnisend has no SMTP relay

Omnisend is an ecommerce marketing automation suite, email, SMS and web push, not an email infrastructure vendor. Its model is contact-and-event centric: you push contacts, products and commerce events in over REST, and Omnisend decides what to send, to whom and when. An SMTP relay is the inverse, your application composes the message and hands over an already-addressed RFC 5322 envelope. A message submitted that way arrives with no contact record, no consent state, no event payload and no segment membership, so none of Omnisend’s segmentation, frequency capping, attribution or automation logic can apply.

The commercial shape reinforces it. Plans are priced per contact tier with a bundled email allowance-250 contacts and 500 emails on Free, 6,000 at the 500-contact Standard tier, unlimited from the 2,500-contact Pro tier. There is no per-message billing unit, which is what a relay product needs. The API reference confirms it from the other side: 19 guides and 130+ endpoints across Events, Contacts, Products, Campaigns, Segments and Automations, without one SMTP resource, credential endpoint or port.

What you actually need instead

Searches for “Omnisend SMTP settings” resolve to one of three jobs. Find yours below.

Sending transactional email

Order confirmations, shipping notices and checkout recovery run on event-triggered workflows. Your backend emits POST /api/events with a contact, an eventName and an origin; the endpoint answers 202 Accepted and any workflow subscribed to that name builds and sends the message. Standard names are documented-started checkout, placed order, paid for order, order fulfilled-and custom events are declared via the event metadata endpoints.

Two consequences. Delivery is asynchronous: 202 means the event was accepted, not that mail was sent, so it is not a receipt the way a relay’s 250 is. And if no workflow listens for that name, nothing happens and nothing errors. Where legal or financial obligation attaches to delivery, use Postmark or MailerSend and keep Omnisend for marketing.

Connecting a CMS, store or custom app

For WordPress and WooCommerce, install the official wp-omnisend plugin rather than looking for credentials, it syncs customers, orders and cart events, with bridge plugins for SureCart, Gravity Forms, Contact Form 7 and LifterLMS. Shopify, BigCommerce, Wix, Ecwid and PrestaShop have one-click native connections. For a custom storefront, use the REST API plus the JavaScript snippet: contacts to /api/contacts, catalog to /api/products, behaviour to /api/events. Bulk backfills use /api/batches, capped at 100 actions.

Routing WordPress and application notifications

Password resets, admin alerts, order status mail and contact-form deliveries are system mail. Omnisend cannot carry them, and no plugin setting changes that. Install WP Mail SMTP or FluentSMTP and point it at a relay you control. Omnisend’s guide names SendGrid, Mailgun, Postmark, MailerSend, Amazon SES and Brevo as the services those plugins pre-configure. SMTP2GO and Resend also suit small stores. Run it alongside Omnisend, not instead of it.

Sending domain authentication

This is the real answer for most people who searched for Omnisend SMTP settings. Authentication is purely DNS, no credentials at any point, and since Gmail and Yahoo enforced bulk-sender rules, an unauthenticated domain is the commonest cause of campaigns landing in spam.

SPF and DKIM setup

Go to Store settings › Domains › + Add domain, choose Email as the type, pick your DNS provider (or “I don’t know”, which makes Omnisend look it up via who.is and tailor the instructions), then enter the exact domain or subdomain. Omnisend generates three records personalised to your account; add them at your registrar, then click Finish verification. No static values are published: the SPF include and the DKIM selector and key are account-specific, and the SPF string is pre-merged with your other senders. Copy the exact values from your Domains screen. The shape:

; 1. SPF, ONE TXT record only. Omnisend supplies the merged value.
mybrand.com.                    IN  TXT  "v=spf1 include:<value-from-omnisend> include:_spf.google.com ~all"

; 2. DKIM, selector and key generated per account. Use the TXT-format part.
<selector>._domainkey.mybrand.com.  IN  TXT  "k=rsa; p=<public-key-from-omnisend>"

; 3. DMARC, Omnisend generates a compliant record in the same step.
_dmarc.mybrand.com.             IN  TXT  "v=DMARC1; p=none; adkim=r; aspf=r; rua=mailto:dmarc@mybrand.com"

Omnisend recommends the main domain for campaigns (mybrand.com) and a subdomain for automations (news.mybrand.com), keeping promotional reputation separate from lifecycle. Verification usually resolves in about 30 minutes but is allowed up to 48 hours; the Domains screen names the failing record if it stays Unverified.

DMARC alignment

Omnisend’s guidance is explicit: set DMARC to p=none with SPF and DKIM alignment relaxed. Relaxed alignment matters because an organisational-domain match then suffices, mail authenticated on news.mybrand.com still aligns with a policy at mybrand.com. A record meeting the Gmail and Yahoo bulk-sender requirements is generated in the Domain Authentication step, so hand-writing one is optional.

Start at p=none with a rua address collecting aggregate reports, and move to quarantine or reject only once they show every legitimate stream passing. Omnisend, your relay, your helpdesk, your invoicing tool. Tightening before that inventory is complete is the fastest way to bounce your own receipts. Branded click tracking, shipped February 2026, is configured on a separate link domain and does not affect alignment.

Sending limits

There is no emails-per-hour figure or concurrency ceiling, because there is no relay. What Omnisend documents is plan volume and API throughput, both enforced per brand.

Test sends are throttled separately and catch people out during setup: campaign tests on Free are capped at 100 per 24 hours and 50 per rolling 3-hour window, automation tests at 50 per 24 hours on every plan including Pro, and every test at 5 recipients. Counters reset at UTC midnight.

Common mistakes

Pairing Omnisend with an SMTP provider

Recommended setup

Split by message class, not by domain. Marketing and lifecycle mail, campaigns, cart recovery, post-purchase series, win-backs, goes through Omnisend over the REST API or a native store integration, where segmentation and revenue attribution earn their keep. Application mail, password resets, order status, invoices, admin alerts, goes through a dedicated relay, where delivery guarantees and fast bounce feedback matter.

On WordPress: install WP Mail SMTP or FluentSMTP against Postmark, MailerSend, Brevo or Amazon SES, then add wp-omnisend for contact and commerce sync. The two never touch: one owns wp_mail(), the other owns marketing. On a custom stack, point your mailer at the relay and emit POST /api/events wherever commerce state changes.

Keeping the two systems from double-sending or breaking DMARC

The first failure mode is double-sending. If your store already fires a WooCommerce order confirmation over the relay and you also build an Omnisend workflow on placed order, customers get both. Decide per message class which system owns it and disable the other. Be careful with historic imports too, the Batch API documentation warns that imported events fire live automations regardless of timestamp, so pause those workflows first.

The second is DNS. If both systems send from the same domain they must share one merged SPF record, the most common breakage in a paired setup. Cleaner is to separate at the subdomain level: campaigns on mybrand.com, Omnisend automations on news.mybrand.com, transactional relay on mail.mybrand.com. Each subdomain carries its own SPF and DKIM, relaxed alignment keeps them aligned to the DMARC policy at mybrand.com, and a reputation problem in one stream cannot contaminate the others. One caveat: third-party DNS observations suggest Omnisend’s merged SPF value includes Mailgun infrastructure, but Omnisend does not publish that include, read it off your Domains screen.

Frequently asked questions