Our verdict: split them when the app or store sends mail on its own
A newsletter platform is built for sending one campaign to many people. A transactional service is built for sending one message to one person the instant something happens: an order, a password reset, a login code. If your website or app needs to send those, use a transactional service or add-on rather than forcing them through newsletter automations.
Who this fits: small stores, SaaS products and booking sites with their own checkout or login. Who can skip it: businesses whose store or booking platform already sends receipts and resets for them; check its settings first.
How the two are defined
The FTC's CAN-SPAM guide treats commercial content as content that advertises or promotes a commercial product or service [1]. Transactional or relationship content facilitates an already agreed-upon transaction or updates a customer about an ongoing one [1]. The FTC says it reads these categories narrowly [1]. This is a US definition and not legal advice; other countries have their own rules.
| Message | Likely category under the FTC guide | Why |
|---|---|---|
| Order confirmation | Transactional [1] | Confirms a transaction the recipient agreed to |
| Shipping or delivery notice | Transactional [1] | Delivers goods under an agreed transaction |
| Password reset or account change | Transactional [1] | Change to an ongoing account |
| Product recall or security notice | Transactional [1] | Safety or security information about a purchased item |
| Weekly newsletter with offers | Commercial [1] | Promotes products or services |
| Receipt with a promotion at the top and a sale subject line | Commercial [1] | Fails the primary purpose test: ad-like subject, transactional content not mainly at the beginning |
What each tool offers for transactional email
| Tool | Transactional option | Published price |
|---|---|---|
| MailerLite | Does not offer SMTP; suggests an automation workaround via API and points to MailerSend for SMTP relay [3]; pricing page shows a Try MailerSend link [4] | Not applicable |
| MailerSend Free | 500 emails a month, 100 daily API requests, 1 domain, 1 template [5] | $0 [5] |
| MailerSend Hobby | 5,000 emails a month, 1,000 daily API requests, 1 domain [5] | $7/month billed monthly, lower with yearly billing; extra emails $1.50 per 1,000 [5] |
| Moosend | Transactional API [7]; the plan comparison marks transactional emails as not included on the trial or Pro, an add-on for Moosend+, and included in Enterprise [6] | Custom quote; no public price [6] |
Decision checklist
- Does your store, booking tool or app already send receipts and resets? If yes, keep using it and brand the templates.
- Do you need messages sent within seconds of a user action, through an API or SMTP? That points to a transactional service.
- Count monthly transactional volume and the busiest day; MailerSend Free caps daily API requests at 100 [5].
- Use a separate From address for each category, as Gmail's guidelines suggest, and don't mix content types in one message [2].
- Keep promotional content out of receipts, as Gmail advises [2]; if you add any, keep it below the transactional details with a factual subject line so the FTC's primary purpose test still points to transactional [1].
- Authenticate the sending domain for both services; see our authentication guide.
Worked example: a small store's monthly mail
Hypothetical store: 300 orders a month, so about 300 order confirmations and 300 shipping notices, plus a weekly newsletter to 1,500 subscribers. The 600 transactional messages exceed MailerSend Free's 500 a month but fit Hobby's 5,000 at $7 a month [5], assuming the busiest day stays under Hobby's 1,000 daily API requests [5]. The newsletter stays on the marketing platform. If the store platform already sends confirmations and shipping notices, the extra service isn't needed at all.
If you send more than 5,000 messages a day to Gmail accounts, Gmail's stricter bulk sender rules apply, including one-click unsubscribe for marketing and subscribed messages [2].
Questions before you decide
Can a receipt include a promotion?
Legally it can, but the FTC says a mixed message is treated as commercial if a reasonable reader of the subject line would expect an ad, or if the transactional content does not appear mainly at the beginning. Gmail's sender guidelines go further and say not to include promotions in sales receipt messages. Keep receipts promotion-free if you can.
Do transactional emails need an unsubscribe link?
Gmail's one-click unsubscribe requirement for senders of more than 5,000 messages a day applies to marketing and subscribed messages. The FTC also treats qualifying transactional or relationship messages differently from commercial ones, but reads those categories narrowly.
Should receipts and newsletters use the same From address?
Gmail's sender guidelines say messages of the same category should share a From address, with an example of separate addresses for receipts, promotions and account alerts. Gmail prefers sending everything from one IP address, but if you must use several, it says to use a different IP for each message type.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- FTC: CAN-SPAM Act, A Compliance Guide for Business Accessed 29 Oct 2026
- Gmail Help: Email sender guidelines Accessed 29 Oct 2026
- MailerLite Help: Does MailerLite offer SMTP? Accessed 29 Oct 2026
- MailerLite pricing Accessed 29 Oct 2026
- MailerSend pricing Accessed 29 Oct 2026
- Moosend pricing Accessed 29 Oct 2026
- Moosend: Transactional emails Accessed 29 Oct 2026
Sources link directly to providers. Product buttons may use separately labeled affiliate links. Read our disclosure.