BE/src/mail/mail.module.ts

import { MailerModule } from '@nestjs-modules/mailer';
import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { join } from 'path';
import * as Joi from 'joi';
import { HandlebarsAdapter } from '@nestjs-modules/mailer/dist/adapters/handlebars.adapter';

@Module({
    imports: [
        ConfigModule.forRoot({
            isGlobal: true,
            validationSchema: Joi.object({
                MAIL_USER: Joi.string().required(),
                MAIL_PASS: Joi.string().required(),
            }),
        }),

        MailerModule.forRootAsync({
            imports: [ConfigModule],
            useFactory: (configService: ConfigService) => ({
                transport: {
                    host: 'smtp.gmail.com',
                    port: 587,
                    //   ignoreTLS: true,
                    secure: false,
                    auth: {
                        user: configService.get<string>('MAIL_USER'),
                        pass: configService.get<string>('MAIL_PASS'),
                    },
                },
                defaults: {
                    from: `"Carnet APP" <${configService.get<string>('MAIL_USER')}>`,
                },
                template: {
                    dir: join(__dirname, '../../..', 'public', 'mail-templates'),
                    adapter: new HandlebarsAdapter(),  // import from '@nestjs-modules/mailer/dist/adapters/handlebars.adapter'
                    options: {
                        strict: true,
                    },
                },
            }),
            inject: [ConfigService],
        }),
    ],
})

export class MailModule { }