While the Vercel platform does not block outgoing SMTP connections, it is recommended to use a third-party service to send email.
To send emails from Vercel without restrictions, we recommend the use of a third-party mail services:
By using one of the services listed above, you will also benefit from analytics, scheduling, and many other features exclusively available from a specialized service.
If you wish to use SMTP rather than a third-party mail service, it is essential that you
await the sending of the message, this can take a few seconds depending on the provider and library used.
The reason for this is because as soon as the response is sent by the Serverless Function to the client, any synchronous work being completed in the background will be paused and may be continued when the function is called once again.