Comparison pages written by the vendors themselves all end the same way: with themselves winning. So we ran our own test. One domain, one set of authentication records, and the same five messages — a simple text send, a designed template, a batch of a thousand, a deliberately broken address, and a webhook-reliant automation — pushed through Mailchimp, SendGrid, Resend, and Brevo. Here is what actually happened.
Setup time, measured
Resend was fastest to a verified domain and a first delivered message: well under thirty minutes including DNS propagation on our registrar. Brevo was close behind. SendGrid took about an hour, mostly because its domain authentication flow has more steps and its dashboard buried the SPF guidance we needed. Mailchimp took the longest, largely because its marketing-first onboarding assumes you will do things like import a list and design a campaign before you care about API keys — which, to be fair, is its audience.
The API, felt with hands
We built the same sending function four times. Resend’s was ten lines and we never opened the documentation twice. SendGrid’s needed the most boilerplate but exposed the most knobs — per-message suppression handling, custom args, send-at scheduling. Brevo’s API was straightforward, and having transactional and campaign data in one account removed a sync script we needed elsewhere. Mailchimp’s transactional engine (the product once called Mandrill) is an add-on with extra pricing, and it shows its age; most Mailchimp customers never touch it.
Deliverability to our test seeds
We seeded Gmail, Outlook, Yahoo, and a self-hosted mailbox, and checked placement over 72 hours. All four delivered the plain-text message cleanly once domains were authenticated — modern platforms have mostly solved the basics. The designed template was where they diverged: the two marketing-first platforms (Mailchimp, Brevo) placed best in Gmail’s Promotions tab handling and inbox placement overall, while the API-first pair performed equally well once we fixed one template-weigh issue. The deliberate bad address bounced correctly on all four, but Resend and SendGrid surfaced the cleanest error signals to our code.
The scoreboard
| Platform | Best at | Weakest at | Pricing shape |
|---|---|---|---|
| Mailchimp | Campaign design, ecosystem, reporting | Transactional email, contact-based billing creep | Contacts stored |
| SendGrid | Scale, deliverability tooling, webhooks | Dashboard complexity, dated DX | Volume sent |
| Resend | Developer experience, modern SDKs | Depth of enterprise controls | Volume sent |
| Brevo | All-in-one channels, unlimited contacts | Reporting depth, daily send caps | Emails per day |
What we actually recommend
Marketing newsletters with a non-technical team: Mailchimp first, Brevo if contact-based pricing stings. Product transactional email: Resend for new projects and modest volume, SendGrid when scale or enterprise controls dominate. Small teams wanting one bill for everything: Brevo. There is no absolute winner, and anyone telling you otherwise is selling something.
Where to start
Once you pick, do not skip the unglamorous part: authenticate your domain properly with our SPF, DKIM, and DMARC guide, then warm up gently — our domain warmup walkthrough has the schedule we use.