Transactional Email Services Compared 2026: Resend, SendGrid, Mailgun, SES, Brevo
Form notifications, order confirmations, and account verification emails shouldn't go out from your company mailbox or Gmail. We compare free tiers, pricing, and best fit across six email services, plus how we actually moved our emails out of spam and into the inbox.
Once a website goes live, there are always emails the system has to send on its own: form submission alerts, order confirmations, sign-up verification codes, and password reset links.
Many sites start out sending these through their company mailbox or Gmail's SMTP (the server used to send mail). It works, but sooner or later something breaks: the account gets locked for sending too much, emails land in spam, or customers never receive their verification codes. These emails belong with a dedicatedtransactional email service。
This article compares six common services, with prices shown in USD, and shares the settings we actually use across several of our systems.
Why you shouldn't send from your company mailbox or Gmail
Sending limits are low.Regular mailboxes are built for people, not for systems sending in bulk. The service behind our own company mailbox, for example, caps the whole account at 20 emails per day. One spammed form and it's gone.
Emails land in spam more easily.We tested it: on the same new domain, a test email sent from a mailbox passed all three sender authentication checks and still landed in Gmail's spam folder. Sent through an email service, it went straight to the inbox. A new domain always needs time to build reputation, but dedicated email services run well-maintained sending servers, so you get off to a much smoother start.
A locked account takes your incoming mail down with it.If a system bug fires off a flood of emails, it's your company mailbox that gets locked, and your team can't even receive mail.
Six email services compared
| Service | Free tier | Entry paid plan (USD) | Best for |
|---|---|---|---|
| Resend | 3,000 emails/month, 100/day | About US$20/month for 50,000 emails | Developers and new projects; easiest setup |
| Brevo | 300 emails/day | About US$9/month for 5,000 emails | Most generous free tier; also handles newsletters |
| Mailgun | 100 emails/day | About US$15/month for 10,000 emails | Established player with thorough reporting |
| Postmark | 100 emails/month (trial-level) | About US$15/month for 10,000 emails | Transactional email where deliverability matters most |
| Amazon SES | 3,000 emails/month for the first 12 months | About US$0.10 per 1,000 emails | High volume, in-house engineers, already on AWS |
| SendGrid | 60-day trial only | From about US$19.95/month | Legacy systems already using it |
How to read this table:For small sites sending fewer than 100 emails a day, the free plans from Resend or Brevo will last a long time. Once volume gets truly large (hundreds of thousands per month), Amazon SES is so cheap it's barely worth calculating, but you'll handle more of the setup yourself.
SendGrid used to be synonymous with "free email sending," but its forever-free plan is gone and only a trial remains. Plenty of older tutorials still recommend it; we don't suggest starting new projects on it.
Our approach: Resend
The booking systems, membership systems, and client dashboards we build all send their notification emails through Resend. Three reasons:
- Simplest setup.Add your domain, paste a few DNS records, grab an API key, and you're sending.
- A Tokyo data center.The sending servers are close to Taiwan.
- API keys can be scoped.Each system gets its own key that can only send, and only from one specific domain. If a key ever leaks, whoever has it can't access other data or impersonate other domains.
One pitfall we've hit: domain verification can sometimes sit at "pending" for a long time. Compare your DNS records character by character, and make sure there's no stray whitespace and that your DNS provider hasn't automatically appended the domain to the end.
We alsoopen the accounts under the client's name. The client's system sends through the client's own email account, so billing and sending logs belong to them, and they can take everything with them when our engagement ends.
Three steps to set up an email service
Whichever provider you choose, the process is much the same:
1. Verify your domain.The service gives you a few DNS records to add to your domain's DNS settings. They prove that "this email really was authorized by this domain":
- SPF: Lists which servers are allowed to send email using your domain.
- DKIM: Adds a digital signature to each email so the receiving server can verify it hasn't been tampered with.
- DMARC: Tells receiving servers what to do with emails that fail authentication.
2. Don't overwrite your existing settings.If your domain already has a company mailbox, it already has an SPF record. A domain can only have one SPF record, so merge into it rather than adding a second one. If you're unsure, many email services can pass verification on DKIM alone, so you don't need to touch SPF.
3. Set the sender and reply-to addresses separately.Emails sent by the system can use a sender address like notify@你的網域, with the reply-to set to an address a real person checks, such as hello@你的網域, so customer replies actually reach someone.
FAQ
Which email services are free?
Brevo offers the most at 300 emails per day; Resend gives 3,000 per month (capped at 100 per day); Mailgun allows 100 per day. Amazon SES only has a free tier for the first year, and SendGrid now offers just a 60-day trial.
Can I send website form emails through Gmail's SMTP?
You can, but we don't recommend it. Gmail has a daily sending limit, and the sender can only be your Gmail address. If a system bug sends a flood of emails, it's your Gmail account that gets locked. For website form notifications, an email service's free plan is all you need.
What if all my emails are going to spam?
First confirm that SPF, DKIM, and DMARC are all set up and passing. If everything passes and emails still land in spam, it's usually because the new domain has no reputation yet. Sending through a reputable email service and avoiding content that's all links or images will gradually improve things.
Can I send newsletters with these services?
Some of them. Brevo and Resend both have newsletter features (Resend's free plan lets you send newsletters to up to 1,000 contacts). But newsletters must include an unsubscribe link, and it's best to use a different sender address from your transactional emails, so spam complaints about marketing emails don't drag down your verification code emails.
What's the difference between transactional and marketing emails?
Transactional emails are what the system sends in response to something a customer did: order confirmations, password resets, booking reminders. Marketing emails are ones you send on your own initiative: newsletters, promotions. Transactional emails don't require subscription consent and have the highest delivery requirements; marketing emails require consent and must allow unsubscribing.
Make sure your website's emails get delivered
Notification emails may seem like a small detail, but if customers don't get their verification code, they'll assume your website is broken. When we build websites and systems, we set up the email service, DNS verification, and sender and reply-to addresses together, with accounts opened under the client's name. Details are on ourwebsite design service page. For choosing a company email provider, see ourbusiness email recommendationsarticle.
Prices are based on publicly available information as of November 2026, in USD. Email service pricing changes often; please check each provider's official website before purchasing.