Yes, Lettermint looks great if you need both transactional and marketing emails. But it's a bit weird that the OP selected Lettermint over Scaleway for just transactional emails when they use lots of other Scaleway services.

https://www.scaleway.com/en/transactional-email-tem/

[EDIT] Found the answer from the OP:

> To be honest I implemented Lettermint before I migrated to Scaleway, so I didn't even look at TEM