New User Registration and SMTP

Hello there.

We use an internal mail gateway, and the wp-mail-smtp plugin to point at the gateway. No problem sending test emails.

When I try to register a new user however, and send them an email, the wordpress admin page says it’s sent, but I know it hasn’t sent the email.

I’ve read up and it seems that the new user registration uses mail, which uses sendmail.

Is there a way to tell the new user registration to use the smtp settings defined in the wp-mail-smtp plugin?

Or is there another plugin I can install to send ALL emails via SMTP?

Any help, greatly appreciated.