I use this with Brevo and it works great!

thanks for providing this great free plugin to help get WP mail delivered every time. For transactional email under 300 per day, Brevo is free and quick to set up with WP Mail SMTP, once you know what you’re doing! You’ll need access to the domain records, and the clients email account (unless you have them on the phone while you are setting this bit up), because you have to 2FA the email address. After that’s done, it’s just a couple more steps and it’s sorted. Note to self; I set up a new account for each client with Brevo (ie; using their email address), because there is no option to set up as Manager, under one Brevo login, that I am aware of.