There are sites partnered with SendGrid who can offer up to 12k emails/month for free, even nowadays. All you have to do is have them provision the account for you and ensure access controls are in place on the partner’s side (only 1 login on the SendGrid site, accessed via the partner)
Not sure how much I should say here (don’t want them to discontinue the service or anything like that, especially with ESPs moving away from generous free offerings), but would be more than happy to point you in the right direction if you can’t find it.