version 5.0.1+ - domain.enter() is not a function on connection close

[lukeselden]

Issue - When connection.close is called (after calling client.sendAsync) an uncaught error gets triggerd:

TypeError: domain.enter is not a function
at SMTPConnection.emit (node:domain:551:10)

Cause - This behavior was introduced in v5.0.1 on fix for #350

Reason - NodeJS's deprecated internal 'node:domain' module assumes a EventEmitter's domain property is an object whenever you call .emit - Relevant node.js code. I found this because the node:repl module imports the domain module in node version 24 (not in v26)

To Reproduce -

// in node v24 imports the 'domain' module
import node_repl from "node:repl";
// this till trigger issue in v26 as well
import domain from "node:domain";

import { SMTPClient } from 'emailjs';

const client = new SMTPClient({ host: '127.0.0.1', port: 25 });
// triggers error
client.smtp.close();

// TypeError: domain.enter is not a function
// at SMTPConnection.emit (node:domain:551:10)

Possible fixes - rename SMTPConnection.domain to _domain, use EventTarget instead of EventEmitter, or other reference method?

Workaround

import { SMTPClient } from 'emailjs';
import { EventEmitter } from 'node:events';

const client = new SMTPClient({ host: '127.0.0.1', port: 25 });

// check if node:domain behavior is active
if (EventEmitter.usingDomains) {
    const domainName = client.smtp.domain ?? '';
    // mock the Domain object
    client.smtp.domain = {
      enter() {},
      exit() {},
      // still treated as a string otherwise
      [Symbol.toPrimitive](hint) {
        return hint === 'string' ? domainName : null;
      }
    }
}