Snippet: Example e-mail sending class #4
Description
Code to test relaying mass email through primary mail server.
import type { SMTPConnectionOptions } from 'emailjs';
import { Message, SMTPClient } from 'emailjs';
import PQueue from 'p-queue';
export type AddressList = {
from: string;
to: string[];
};
/** Internal configuration used by emailjs to send mail, see https://www.npmjs.com/package/emailjs for all options. */
export type EmailConnectionConfig = Partial<SMTPConnectionOptions>;
export default class Emailer {
/** stop sending mail after this many items are in the queue */
private readonly mailQueueMaxSize = 512;
/** The minimum amount of time between sending each email. */
private readonly globalMailThrottle = 750;
// throttle mail sending using a promise queue
private readonly mailQueue = new PQueue({ concurrency: 1, interval: this.globalMailThrottle, intervalCap: 1 });
private client: SMTPClient;
constructor(options: EmailConnectionConfig) {
this.client = new SMTPClient(options);
}
public async send(addresses: AddressList, subject: string, text: string) {
if (!addresses) {
console.warn(`Not sending email. Address list looks falsey.`);
return;
}
const from = addresses.from;
if (!from) {
console.warn(`Not sending email. No from address is configured.`);
return;
}
if (addresses.to.length === 0) {
console.warn(`Not sending email. No addresses are configured to send.`);
return;
}
const to = addresses.to.join(', ');
if (this.mailQueue.size >= this.mailQueueMaxSize) {
console.error(
`Dropping outgoing email. There are currently too many items in the email queue. (Queue size= ${this.mailQueue.size}, maximum=${this.mailQueueMaxSize})`
);
return;
}
await new Promise<void>(resolve => {
const mailTask = async () => {
try {
console.log(`Sending email to ${to}...`);
await this.client.sendAsync(
new Message({
from,
to,
subject,
text,
'content-type': text.startsWith('<!DOCTYPE html') ? 'text/html; charset="UTF-8"' : undefined,
})
);
console.log(`Sending email to ${to} [SENT]`);
console.log(`There are`, this.mailQueue.size, 'items left in the mail queue');
resolve();
} catch (err) {
console.error('Error sending email!', `(Subject: "${subject}")`);
console.error(err);
console.log('Putting this email to the back of the send queue...');
void this.mailQueue.add(mailTask);
}
};
void this.mailQueue.add(mailTask);
});
}
}Source: eleith#315 (comment)