If you are building a SaaS, you need to send emails to users. It is generally not a good idea for you to build out SMTP rails from first principles, which is where the concept of an "email service provider" comes in.
This is a distinct product + infrastructure from "email providers" writ large like Mailchimp or Substack or Klaviyo. Those companies provide email marketing service. (Notably, two providers listed below — Mailchimp and Sendinblue — provide both email marketing and transactional email services, but we are only listing their transactional email services here.)
Postmark is the best ESP for most people. It is more expensive than Amazon SES, but unless you're thinking about sending close to a million emails every month the price difference is negligible compared to the superior admin interface, high baseline deliverability, and excellent support.
|Service||Free tier?||10K emails||100K emails||1M emails||Dedicated IP?||Postmark||—||$15.00||$115.00||$695.00||$50.00||SendGrid||100/day||$19.95||$34.95||$449.00||$55.00||Mailchimp||—||$20.00||$80.00||$720.00||$29.95||Mailgun||5000/month||$5.00||$75.00||$650.00||Free at 100k emails||SMTP.com||—||$25.00||$80.00||$500.00||Free at 100k emails||AWS SES||—||$1.00||$10.00||$100.00||$24.95||SparkPost||500/month||$20.00||$30.00||$525.00||Free at 250k emails||Sendinblue||300/day||$15.00||$65.00||$550.00||Free||Mailjet||6000/month||$15.00||$95.00||—||Free at 100k emails||SocketLabs||2000/month||$40.00||$80.00||$515.00||Free at 100k emails||MailPace||—||$10.00||$100.00||—||—||Resend||100/month||$20.00||$35.00||$400.00||$30|
Plus some caveats and miscellany:
I have no relationship with any of the organizations listed besides being an active customer of four of them (Postmark, SendGrid, Mailgun, and SES), and do not receive an affiliate cut from any of the services mentioned. I have personally integrated with each provider listed below, and have used them to power Buttondown, a newsletter service that sends millions of emails every month.
Well, yes and no. SES is certainly the best-priced option for most use cases, but the developer experience is... not great. The admin tooling is on par with the rest of AWS's dashboard, which is to say it is an acquired taste. If you're sending less than 100k emails/month, I'd personally recommend using another provider whose tooling is more user-friendly; the $10 you save per month is not worth the time you'll spend having to wire up all the things you need.
Let's pretend that every single email in the world has a "quality score" associated with it. The higher that quality score, the more likely it is to be delivered to the inbox and avoid the spam folder. One of the many, many factors that goes into that quality score is the IP address that the email is sent from. IP addresses that have been associated with low-quality emails in the past are more likely to be associated with low-quality emails in the future, and so a 'low quality' IP address is going to hurt your quality score.
All ESPs have two options for sending email: shared IP where you're sending mail from a pool of IPs that are shared with other customers, and dedicated IP where you're sending mail from one or more IP addresses that is only used by you.
You might read those two paragraphs as "okay, so I want a dedicated IP no matter what." But that's not necessarily the case. If you're sending a small volume of email, you're probably better off using a shared IP; an IP address with low or spiky volume is going to be associated with low quality.
Bluntly – no. Some shared IPs are better than others. ESPs have one main lever to keep their shared IPs in good standing with the email providers: they can kick off customers who are sending volume that is driving down their IP address's quality score. The absolute best shared IPs are ones that are the most stringent about kicking off customers who are sending low-quality email. In my (anecdotal, unscientific) experience, Postmark has the best shared IPs and AWS has the worst.
(Again, this only really applies if you're sending a small volume of email. These particulars are less important if your sending volume warrants a dedicated IP.)
You're likely in a position to negotiate a better deal than sticker rate for your volume!
That was true in the past, but they've since changed their policy. You can now use Postmark for marketing emails.
I have not used it myself and cannot vouch for its quality or merit, but Postal may fit your bill.
Okay, fine. Use Postmark. I think their interface is the best.
Email me! I'll add it.
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