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Comment by mbesto | Hacker News Reader

Ya, but why does a transactional email service have anything to do with the front-end....I feel like I'm missing something very obvious but I can't seem to figure it out...

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I don't mean this snarkily, but have you ever used a transactional email service? Literally all of them support frontend, I'd much rather use something like React than "Handlebars" (which Sendgrid requires https://docs.sendgrid.com/ui/sending-email/how-to-send-an-em...)

I've used pretty much all of them and in most cases you're sending the request via some message queue (front-end -> async to back-end -> message queue -> async returns to back-end DB), which is managed on the backend. I'm scratching my head as to why relying on the browsers threading to do seems like it offers any advantages...

I think he may have wondered how would, say a Python backend using Resend Python SDK, render a React Email template and send it. Their API docs [1] for "Send Email" has an option for specifying a 'react' component to render the message but it's only available on the NodeJS SDK. Otherwise you pass HTML and/or Text.

Personally, I was expecting the api to optionally accept a React Template, along with the Data, where upon the Resend api would Render it (or fail) then Send it. Passing a 'preview' param would return the rendered HTML/Text (for testing) - just a thought.

[1] https://resend.com/docs/api-reference/emails/send-email

Exactly this.

Said differently - how many devs out there are screaming "I really need to send transactional email via React", when most apps are sending it via Python, Ruby, PHP, Java, and (back-end) JS.

Preface: I'm with you on this.

But I think the targeting here is for a certain generation of companies where there is a very distinct backend/frontend split OR companies where everyone is a JavaScript dev (and the backend is Node). The backend folks send the email content and the frontend folks are responsible for building the presentation-layer stuff. The thinking here, I believe, is that those frontend guys do all their other work in React, so when they're given these transactional emails to build, they'd prefer to keep working in React. I think?

I think you’re conflating terms (or possibly concepts) here. This isn’t about sending emails via React; this is about sending HTML emails generated from React components via a backend. The examples shown on the landing page are of Node.js, Next.js route handlers and Remix loader functions, the latter two being fancy abstractions over Lambda functions (or isolates).

I agree that sending an email from React doesn’t make a lot of sense, but that’s not the target at which this is aiming.

Er, you can send the emails via whatever backend service you want. React merely acts as a templating language and when compiled down to HTML, you can then send the resultant file with Python, NodeJS, etc.

But the code populating and sending the email is rarely (ever?) Front end code

Sure, but presumably you want your emails to generally match the aesthetic of the rest of your product, which is easier if you can use the same tooling to make them as you do the frontend of your product.

React doesn't do its own styling though, and since email will not run js, you are basically talking about css at this point

Maybe that is the secret sauce of this service. They render the email with react and automagically convert that to something that works for email?

I think they literally just use React as a templating language, basically. You write React components and this service renders them down to email-friend HTML. Like SSR but for email.

I've worked at a couple companies (medium-scale) with home grown email solutions. The server-side rendered templating grew into being used for HTML email as well. It helped the backend devs as the tech that rendered the webpages also rendered the emails (all server side rendering), and the frontend devs needed less training to go from just frontend to frontend + emails. It was sort of a path of least resistance thing and it did have its drawbacks.

> It was sort of a path of least resistance thing and it did have its drawbacks.

This makes sense, but ya aren't there serious scaling implications to this?

Not really? The system worked as designed for the years I was there and sent _many_ emails. Rendering a template was never so taxing as to not scale. From a workflow perspective, each email was a template file, so if you had a ton of emails it was easy to parallelize the work across frontend devs

Simpler websites often don't need a backend anymore (beyond automated, managed hosting). Many of them can just e a frontend package that can be deployed anywhere as static output files (CDN, any file host, Vercel, Netlify, Cloudflare Workers, S3, etc.)

In such a system, sending an email is traditionally a pain (well, email is always a pain, but even more so when you don't have a dedicated backend). Being able to fan that out to an API call (plus a template system already in your frontend's language) just means it's easier.

The API part handles the transactional email and deliverability and all that. The React part helps with the handcrafting of emails using a familiar layout composition language (React). But that part is entirely optional; it's a separate open-source project anyway and you can use the API without React at all if you so choose (or conversely, use the React email templates without Resend).

This makes sense, but what if you're using a message queue to send transactional emails? Why would you put that logic on the browser?

Not quite sure I follow. Do you mean your frontend sends a "send message X to user Y" request to your backend, which then enqueues it internally and handles the actual SMTP later?

That part of the logic wouldn't be in the browser (unless you're purposefully trying to emulate SMTP on the client for some reason). In Resend, for example, a 200 just acknowledges that their API successfully received your request and will attempt delivery soon. It doesn't necessarily mean the email was either sent from their SMTP servers or received by the recipient's server client. You can check delivery status later on in the dashboard: https://resend.com/docs/dashboard/emails/introduction#unders...

(And then optionally receive that as a webhook later on, if you want to notify the user of success: https://resend.com/docs/dashboard/webhooks/event-types#email...)

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Edit: In case it wasn't clear, the value of something like Resend or (SES or SendGrid or whatever) is that you don't HAVE to write logic to handle the tricky parts of email delivery. You just send an API call to someone else's transactional email service and let them worry about all that.

Bigger companies with dedicated staff/teams might want to inhouse a lot of that stuff, but there are a lot of smaller companies (or non tech companies) that still need to do transactional emails but don't necessarily want to maintain it in-house.

In a resource-constrained team/org, it's the difference between a full-stack dev who has to split time between making the website and maintaining the backend(s) and infra, vs a cheaper frontend Javascript dev who can focus solely on the frontend UX/marketing/branding/etc.. The latter can matter more for direct-to-consumer companies who don't necessarily care about the backend as long as it works and isn't too expensive... those 3rd party services are usually much cheaper than hiring even a junior dev/sysadmin.

> Do you mean your frontend sends a "send message X to user Y" request to your backend, which then enqueues it internally and handles the actual SMTP later?

No, I'm very familiar with transactional email services and why its superior to SMTP.

> You just send an API call to someone else's transactional email service and let them worry about all that.

100%. But you also need code to do that. Typically the front-end form calls a backend endpoint (a controller for example in MVC) and then the back-end manages the request with the external API. Hence why there are endless docs like this: https://docs.sendgrid.com/for-developers/sending-email/quick...

At scale, those calls are actually handled by a message queue (like Redis). If you let the front-end code handle it, you would likely get throttled by the transactional email service provider.

Ah, I see what you're saying now! Sorry I misunderstood, and thanks for explaining.

That does sound like something better dealt with on the backend at sufficient scale. The Resend API rate limit appears to be 10/sec.

How can you send an email from the front-end without the next scammer using your keys to do the same?

I _think_ the idea is just to use React as a templating language to write HTML emails, rather than dealing with the quirks of email HTML directly; it's not about sending emails from the frontend.

But why use React to do that when you can achieve the same thing on the backend?

https://mjml.io/

The selling point is that this allows leveraging existing React knowledge, as per the founder's comment upthread.

There's also react-mjml, a React wrapper around it. Works great, altho it's easy to mix up React props with mjml props. Just requires devs to actually read the documentation

Unfortunately, the react-mjml library is no longer maintained: https://github.com/wix-incubator/mjml-react#notice-this-proj...

The business wants to maintain the same consistent style with all communications to the customer. A lot of thought goes into design systems, they don't want to throw that away in their emails.

Emails are rendered like websites with a reduced featureset.

This isn't really true. More like static pages targeting a million different rendering engines with unbalanced feature support

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