Send email from Cloudflare Workers

import { Emailssh } from '@emails.sh/sdk';

interface Env {
	EMAILSSH_API_KEY: string;
	EMAILSSH_FROM: string;
}

export default {
	async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
		if (request.method !== 'POST') {
			return new Response('Use POST', { status: 405 });
		}

		const body = (await request.json()) as { email?: string; name?: string };
		if (!body.email?.includes('@')) {
			return Response.json({ error: 'A valid email is required' }, { status: 400 });
		}

		const mail = new Emailssh({ apiKey: env.EMAILSSH_API_KEY });
		const name = body.name ?? 'there';

		const send = mail.send({
			from: env.EMAILSSH_FROM,
			to: [body.email],
			subject: 'Welcome to Acme',
			html: `<p>Hi ${escapeHtml(name)}, your Acme account is ready.</p>`,
			text: `Hi ${name}, your Acme account is ready.`,
			idempotencyKey: `welcome:${body.email.toLowerCase()}`
		});

		// waitUntil keeps the Worker alive for the send after the response has
		// gone out. Without it, returning would cancel the in-flight request.
		ctx.waitUntil(
			send.catch((error) => console.error('emails.sh send failed', error))
		);

		return Response.json({ ok: true }, { status: 202 });
	}
} satisfies ExportedHandler<Env>;

function escapeHtml(value: string) {
	return value.replaceAll('&', '&amp;').replaceAll('<', '&lt;').replaceAll('>', '&gt;');
}

import { Emailssh } from '@emails.sh/sdk';

interface Env {
	EMAILSSH_API_KEY: string;
	EMAILSSH_FROM: string;
	SUBSCRIBERS: KVNamespace;
}

// Add the trigger in wrangler.jsonc:
//   "triggers": { "crons": ["0 9 * * *"] }
export default {
	async scheduled(event: ScheduledController, env: Env, ctx: ExecutionContext) {
		const mail = new Emailssh({ apiKey: env.EMAILSSH_API_KEY });
		const list = await env.SUBSCRIBERS.list({ prefix: 'digest:' });

		// One batch call instead of N requests. The endpoint takes up to 100
		// messages, so chunk anything larger.
		const messages = list.keys.slice(0, 100).map((key) => ({
			from: env.EMAILSSH_FROM,
			to: [key.name.replace('digest:', '')],
			subject: 'Your Acme digest',
			html: '<p>Here is what happened yesterday.</p>',
			text: 'Here is what happened yesterday.'
		}));

		if (messages.length === 0) return;

		ctx.waitUntil(mail.batch(messages));
	}
} satisfies ExportedHandler<Env>;