The short version
The split comes down to trigger and intent. A transactional email fires because the recipient did something — bought, signed up, requested a reset — and it carries the information that action requires. A marketing email is something you decide to send to promote a product, an offer, or a newsletter. That difference in intent is what regulators, mailbox providers, and your own deliverability all key off.
What counts as transactional
A message is transactional or relationship content when its primary purpose is to facilitate, complete, or confirm something the recipient already agreed to. Order confirmations, receipts, password resets, shipping notices, security alerts, account-balance updates, and changes to terms all qualify. The US FTC frames this as the message's "primary purpose" — if a reasonable person reading the subject line would see an ad, it is no longer transactional.
The consent line
In the US, CAN-SPAM lets transactional messages skip most rules — but commercial mail must honor opt-outs and include a physical postal address. In the EU and UK, the bar is higher: under GDPR and PECR, marketing by electronic mail to individuals generally needs prior consent, with a narrow "soft opt-in" for your own existing customers on similar products. Consent must be a clear, positive action and withdrawable at any time. None of this is legal advice — confirm your obligations per market.
Why you separate the two streams
Mailbox providers judge a sending domain and IP by the behavior of the mail that flows through them. Marketing mail draws more complaints, more dormant recipients, and more spam reports than receipts ever will. If both share one stream, a bad campaign can drag down the reputation that delivers your password resets. Splitting them protects the messages a user is actively waiting for. As a customer-engagement platform, fromHello keeps these as distinct sending paths for that reason.
- Separate subdomains — for example notify.yourdomain.com for transactional, news.yourdomain.com for marketing.
- Separate IPs or sending pools so reputation does not bleed across.
- Separate From addresses so recipients and filters can tell the two apart.
- Independent suppression and consent state per stream.
The trap: promotion inside a receipt
The tempting move is to tuck a discount or a "you might also like" block into an order confirmation, riding the high open rates transactional mail earns. The risk is reclassification. If the promotional content becomes the primary purpose — or even sits above the transactional content — the message can be treated as marketing, which means it now needs consent and an unsubscribe. The exemption is narrow by design; it breaks the moment you add promotion. Keep the upsell in your onboarding sequence where consent already covers it.